My pair of UFO25s arrived today and my plan was not to say anything until they'd had at least a few days of burnin. But that didn't work out .

They are configured as balanced mono blocs and after they had been on for 10 minutes, straight from the DAC, no preamp, no fancy fuses and with "B" tubes installed all I could think of was "I'm home." It is like when you get back from vacation, and even though you had a great time and maybe saw amazing things you're really glad you're finally home. I've been listening to a 300B amp exclusively since January, when I sold my UFOs, and I've said many times that it sounds beautiful, but maybe too beautiful for me. And now I'm sure I was right. I can certainly see why a lot of listeners are attracted to the extra tube yumminess of a 300B amp. I'll have (a lot) more to say about the comparison later, but for me the TL;DR is I needed a little more edge. Even at this early stage I can hear the extra detail and a little more bite in e.g. violin bowing or brass.

I'm running the amps overnight into a dummy load and assuming no problems (knock on wood) I'll put in my Synergistic Research Orange fuses and favorite Mullard GZ33 rectifiers tomorrow and do some more listening.  FTR/FWIW I bought the amps without tubes (because I have enough for this lifetime and most of the next already) and started with Sylvania 5931 aka 5U4WG rectifiers, Siemens EL83 power tubes with adapters, Mullard PCC88 input tubes, GE OA3s in back and RCA 0C3s in front. I've collected a whole mess of VR tubes while I've been waiting for the amps and I guess I'm going to have to try all of them...

P.S. The amps are physically beautiful. I felt like the basic UFOs had an understated dignity about their design, but the '25s with the Padauk base and the meters and all are truly a piece of high end audio art.

P.P.S I don't necessarily recommend leaving your amps on overnight but I've done it many times over the years and never had a problem (knock on wood).

Thats awesome James, makes me drool thinking of your mono’s! I also love the look of the meters etc of my 2.1, enjoy your break in..
Randall

James, I missed your announcement until just now, Congratulations!

I look forward to hearing more as you have more time with the new guys, but I'm really happy for you.

Enjoy!
Tony

Congratulations on your new amps CA James. May they bring you much musical enjoyment.

HK

Firstly let me say thank you for all the well wishes. It is getting increasingly hard for me to find the levels of camaraderie and mutual respect elsewhere that are so abundant here.

OK, back to audio. I'm closing in on 30 hours, and feel like I'm through the worst of the breakin. After last nights run the bass has tightened up, the sound stage is bigger with better definition and the sound is both a little more transparent and liquid. I just got done listening to Gemini by Alan Parsons (get it?) and it was amazing. Huge 3D soundscape, razor sharp imaging and just the right amount of tube loveliness. I'm temped to say the best sound I've heard in my house but will hold off for a little while.

When I got my 300B amp I was surprised (and pleased) at how much it sounded like my UFOs. I've spent most of the last year working through my collection of 6SN7 equivalents trying to tweak the 300B sound to where I want it. And just a couple of weeks ago I achieved the best combination yet of 300B yumminess and UFO speed and transparency. But something still wasn't quite right.

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Exactly. I take some pride in my ability to express myself in writing but I'm struggling to find the words to explain what it is about the UFO25s that I like better than the 300B amp. I've said before the UFOs are the perfect balance of truth and beauty. The 300B trades some of the truth for a little more beauty and I want the truth back. And I feel like I have it now. A couple of posters have made photographic analogies to the sound so here's mine:

To me it isn't about the sharpness of image. The 300B was tack sharp, as are the '25s. It is like the 300B "image" was processed with just a little too much saturation and contrast. Nothing offensive, and at first look it can be striking. But on closer inspection something just doesn't seem right. The image looks good, but maybe too good. It isn't that anything is missing necessarily, if anything there too much for my brain to be fully engaged in the experience.

A few technical notes:

I got two amps because I want to run balanced all the way to the speakers, not because of the extra watts. I was pretty sure I had never clipped my UFOs and have confirmed that I can play the 25s way louder than I would ever want to listen without the meters moving or the VR tubes flinching.

My front end is essentially unchanged from a year ago. I'm using one of my favorite "UFO" tube complements in my preamp and the only other changes are updated firmware on my Denafrips DAC and a nicer cables running from my laptop and CD transport to the DAC. All of which were nice upgrades, but nothing game changing.

I confirmed (yet again) that for me, a tube preamp is an absolute necessity. It adds just a little bit of secret sauce to the sound that I've got to have. Perhaps it does for me what a 300B amp does for others.

I put in my favorite GZ33 rectifiers and new SR Orange fuses yesterday. I forget the fuses were brand new so certainly running them in has improved the sound as well, although I noticed a change for the better right out of the box. I haven't done any more tube rolling although I have a long list of tubes to try, starting with O[A|B]3 VR tubes in front and my favorite EL822 power tubes. I may get started on that project later today.

I'm not going to lie, it felt pretty good to update my sig to take the "on order" out of the UFO25 line.




 

More progress, both with the amp (at 40+ hours) and (hopefully) my ability to describe what I'm hearing.

Yesterday I tried 0 A, B and C 3 VR tubes in front, and clearly heard what others have been talking about. For me, the with Mullard PCC88 the A and B were clearly too "bold." Too forward and tightly focused. C seems just right, although for completeness I need to try a D at some point. Am currently running Hytron 0C3s, they sound pretty similar to the RCAs they replaced. Swapped out the GE 0A3s in back with RCA JANs and liked the difference with the EL822 power tubes. Also tried some early 60's 6N5Ps which sounded a little more "300Bish" a little warmer and slightly rolled off on the top and bottom. Not at all unpleasant and not sure if I like them better than the Mullards or not. I'm going to leave them in for a while and then try my Amperex 7308s.

I think I'm getting a handle on the '25 sound vs. the 300B sound. They are more similar than not, much more like each other than what I remember the AR or CJ amps sounded like back in the day. But, I think the 25s are both more dynamic and more transparent. And this gives the sound what I'll call a purity that the 300B couldn't match. I think the 300B rounded off the highs (and the transients) a little and added a warmth and "glow" that sounded gorgeous, but not like any real instruments that I've ever heard. It was also missing the final measure of detail and space that, for me, is the calling card of the UFO family. I don't want to imply the 300B was slow or veiled in any obvious way. While its been years, I feel like it was every bit as fast and transparent as the Pass Alephs I listened to for 20+ years and thought were the last word.  The 25s are just that much faster and more transparent. My UFOs showed me what was possible and the 25's have taken it to another level.

A few more technical notes. With any and every tube set I've tried the amps are dead quiet. Like heat death of the universe quiet. The (AC heated) 300B had a bit of hum I couldn't adjust away and that always was a bit of annoyance.

And yes DD, balanced all the way through. I have essentially a 4 channel system from DAC thru preamp thru the UFO25s.

Wow. Just WOW.

Instead of messing with input tubes I decided to try out the "fancy" rectifiers that I had acquired during the wait but had almost forgotten about. A pair of Cossor "big bottle" 53KUs. I got one for my headphone amp, really liked it and thought it might sound good in the '25s. And I was right. This is transformative. I thought things were sounding good earlier but now I'm kinda in shock. The soundstage is both bigger and more lifelike. The sound is both more liquid and more detailed. Dynamics are fast and perfectly natural. I started doing the audiophile thing of listening to recordings for like 60 seconds and moving on but I couldn't help myself. Mahler symphonies, The Miles Davis Quintet, Led Zeppelin, Rebeca Pidgeon, the Julliard String Quartet you name it, they were there in the room with me. They sound better than real life, not in a warm, beautiful way like I accused my 300B amp of sounding on occasion. But like you have the perfect seat in a perfect hall for listening.

Thanks to my Scottish Heritage I had to work pretty hard to find a couple of these tubes in the 200 dollar range, which is what I was willing to spend. So tube-wise I've got:

Cossor 53KU rectifiers
Mullard EL822 power tubes with adapters
early 60s 6N5P input tubes
Raytheon 0B3s in back
Hytron 0C3s in front.

I hesitate to mess with anything but I'll try the 7308s next. Mine are white label SQ. Back in the (very) early days of the internet a guy sold me 10 lightly used for 20 bucks. Those were the days...

Hey Tony. I'm just a few hours down the 101 (yes, the 101) so if you're up for the drive I'd love to show off my system. I'll even buy you lunch .

As for the 7308s, it didn't go well. They sucked all the air out of the room. The whole sound stage basically collapsed. What kind of VR tube do you like with yours? I was thinking I could improve the situation by going from a 0C3 to a D, but  decided to go with the sure thing instead and put the 6N5Ps back in. I have a whole mess of other input tubes to try, and a set of cryo'd EL822s. I've got a bunch of other rectifiers too, but I can't imagine any of them sounding as good as the Cossors, none of them were as good as the GZ33 in my UFOs.

My UFO25 is number 3, that gives you some idea of how long I've had it and I'll soon order another pair.  I've tried various tube combinations including different CryoTone tube combinations, and, as you are aware I'm Mr. Freeze.

So here's a hint... the best results come from a full CryoTone tube complement BUT, if your going to try one, one that by it self made a significant difference even within the entire CryoTone complement...

try the CryoTone 12AU7-WCL with a good adapter for the input stage.

Honestly, for the first several weeks there were days or hours when it seemed the sound changed to where soundstage flattened, top end became veiled, lacked detail, etc. Some of my favorite tubes, such as the 7308’s didn’t sound great, so I tried changing things but not being fully satisfied. There were moments I wondered if I made the right decision. I had agonized before the purchase if I should get the Sarah instead and on those days I believed I’d maybe chosen wrong. I took Joman’s advice he gave me months before to let the amp burn in for a while before rolling tubes any further, to get a more true sense of what they bring. So I waited it out and for me that worked well. Now most all tubes I have sound great, just bring a little something different. I no longer have any thought that I didn’t make the right decision. Curious? Yes, but I’m so enamored with what I’m getting with my Zen anniversary amp that I find myself perfectly content with this whole preamp/amp stage of my system. I bet if you liked the Amperex with the prior Zen amps, you’ll like them here as well, once the amp settles.

Joman, I did purchase a full compliment of Cryotones (except VR’s) for both amp and preamp. I wasn’t fully happy with the results compared to some of my favorite NOS. I found the 5AR4’s to be slightly too thick for me, in my system. The input tubes sound good to me, so I’ve continued using them on occasion, while the others were put away for a while. I’m not saying they sounded bad, but were just not my preference in my own system. I haven’t put more than 30 hours on them. Do they change much after burning in further? Perhaps they just haven’t opened up fully? I haven’t given up on them just yet so I’ll give them more of a chance. I’ve just been really happy with the combo I have in right now, so haven’t had urge to swap anything.

By the way, I’m just a little farther down, off the 405, so maybe we plan a West Coast Decfest Road Tour?  ;D

... Benadryl??????

Lagavulin...

Thanks Joman. I certainly don’t want to derail or hijack James thread either. Yes, very important to emphasize that my comment was in regards to MY system, and also in MY room with MY preferences. It was not to say the Cryotones were not good sounding tubes. Just that I found a combo of NOS tubes that really work for me. It could have been I didn’t give enough time for the Wathen tubes to settle fully, my amp was still seasoning, or that it wasn’t a “complete” set as the VR tubes weren't cryo’ed. Also, my system may have a bit of room for improvement and my experience may not be as vast as others… I’m still learning a lot about what works and what doesn’t. I intend to get them back out in rotation, as I’m getting more familiar with my systems interplay.

Also, I wanted to express that my experience with burn in was not for James’s benefit or others very familiar with the Decware sound, but for those like me who are still exploring all of this and may be eager to find better sound with their new gear and blaming tube choices on issues with early burn in. There are people who discount burn in, but my experiences were very clear to me. I appreciate your advice on that, Joman.

Editors note re: hijack, off topic etc. This is a thread about UFO25s. Any experience, opinion or random thought you have regarding tubes, break in, or whatever that might be relevant to a UFO25 is absolutely on topic and I'm very interested in hearing a discussion about it. The wealth of experience and opinion is exactly what makes this forum so great.

What is clearly off topic is Single Malt Antihistamine.  But I'm a huge fan and since JOMAN has shown (yet again) that he is a gentleman of refined and elevated taste I have to say that yes, The Ardbeg is some of the best I've ever tasted. I've recently acquired a bottle of Talisker 15 Year Old Special Release that really hits the sweet spot (or peat spot) for me.

Now, back to my amps.

Tried the TFK ECC189s today, which lead me to swap out the 0C3 in front for Hytron JAN (with the anchor) 0D3s. They sound pretty nice, although not exactly what I'm looking for. I like that the bias switch sort of splits the difference between the VR tubes. In other words the 0C3 with low bias is a small step in "focus" from the OD3 with high bias. Then 0D3 with low bias is another step to a more airy presentation. Of course you need to adjust the volume, which I find to be about 2 clicks on the stepped attenuators to give the different settings a fair listen.

What is really interesting is even though I've only had the amps for a few days, and the sound is anything but dialed in I find that I'm listening to a lot more "big" music, like orchestras and big bands than I was with the 300B amp. Big music had always been the majority of my listening, but I think with the 300B amp I was missing some of the detail and dynamics that make orchestral music so involving for me. At the same time it would make individual instruments sound so beautiful that I gravitated to more chamber music, small group and piano solo. The '25s bring back the engrossing orchestral soundscape that I had before with my UFOs, and then some. This is more of the "I'm home" that I referred to in my OP.

I'm familiar how the 0_3 tubes change the sound in the input position. How do they change the sound in the power tube position? I'm guessing it's a subtle variation of what it does in the input position?

The real question is. How many years does listening to two UFO25TH add to a wee dram? Does a 15 year become a 20 year or 25 year??? These are the questions we need to know.

If power isn't a consideration how does the sound change? I found all 0A3 was a bit too rich and forceful. 0B3 in the front vs 0B3 in the back, what is the difference going to be?

He took it back so I'm not in a place to experiment. The sound has been haunting me—in a good way—ever since I spent a few days with it in my system.

As for the 7308s, it didn't go well. They sucked all the air out of the room. The whole sound stage basically collapsed. What kind of VR tube do you like with yours?

Bummer.  I have read there is some debate, perhaps not much, but some, between the Amperex 7308 Green Label and White Lable.  I have both and prefer the Green.  I also followed Joman's advice and tried the Cryo 12AU7 in this location with excellent results. Still, every time I have experimented, I found in my system that the Green Label 7308 won me over.

The voltage regulator I have is Raytheon JAN OD3A and two Cryo OB3 in the back.

James, it may be fair to note that when you talk about truth and beauty with the 300B. . . you are not talking about the Decware SEWE300B "Sarah" amp, correct? Because I find hard to distinguish between truth and beauty with my SEWE300B compared to the SE84UFO3 modded monoblocks I had for five years.

With my SE84UFO3 Monoblocks with all the mods the 6P15P were much better than any other tube types I tried (and I tried them all with high hopes); it may be that the bypass mods make this the case. Also in my case it's the certified activation of the Hazen Grid--I have to have that. I still have about 25 pairs of that tube type. . . and now only one amp (Taboo Mk IV with Mods) that use them.

I too always use the lower powered switch position--that's where the tone is on my systems.

Well, that was easy. I guess I should have done it days ago. My (non-Decware) preamp is also my headphone amp and I was noticing just a tiny bit of veil when I was listening on the 'phones. So I made a tube change on the pre and Bam! The veil is lifted! The '25s are now sounding the way I imagined they would: big, fast, dynamic, liquid and gin clear from the low bass to the high treble. For the last 90 minutes or so I really have been listening to the best sound I've ever heard in my house. Now I really am home.

I guess it just goes to what we all talk about: with resolution like this everything matters. There is still some work to do: there is a little bit of congestion in the sound stage that probably means either 0D3s in front and/or some different input tubes. And then there is all the gratuitous tube rolling, just for fun. I should be pretty close to 100 hours on the amps so if I'm not through the new cap weirdness I think I'm pretty close. Regardless the timing is good because we leave tomorrow for some time with Mrs. CA's family and I can leave the amps off knowing they will sound great when I get home, and will sound even greater going forward.

 

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I personally find gin repellent, but "gin clear" is certainly a thing.

I never used 0A3. . . it just hit with too much "force." 0B3 (I have one pair that is Arcturus, old . . . and so sweet) and 0D3 (many favorites including an RCA pair and a Raytheon pair) seemed to be the ticket for me depending on other tubes in the complement.

It's amazing what voltage regulation tubes do in these amps.

Yes, and even though these B, C and D do theoretically lower the output power, I never really seem to have noticed that.

So if you read Steve’s posts in the 25th anniversary amp thread he explains the VR tubes in detail. But briefly, the voltages posted are the voltage drops across the VR tubes. They are used instead of resistors to set the DC high voltage to the plates of the signal tubes. And they have the added advantage of removing noise from the power. So the greater the voltage drop the lower the operating point of the tubes and the less power they produce, in theory.

But note that “output level” i.e. gain isn’t the same is power. Gain is how much the voltage increases, power is the ability to source that voltage across a load without distortion.

I think that is exactly right. VR tubes were invented to regulate voltage, but in Decware amps they are used to drop, and as a bonus, filter it. They replace resistors for this purpose.

LiquidBlue, How many hours do you have on your amp now? If it's less than 500-1,000—not sure the exact number—then it will still be changing. Decware amps are so pure that every little thing shows up and it really does take a LONG time for them to stop the swings of burnin.

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Yes, get a good handle on what you're hearing.  What you like and what you don't like.  Then step back, so to speak, if there's something you don't like try to figure out if it's as a result of the tubes or possibly something else upstream that is now being revealed.

If you haven't tried the CryoTone 12AU7-WCL long plate, try it!  But not right away.  Listen to what you have for at least 40 hours and then try the CryoTone 12AU7-WCL in the UFO25 input position with a good adapter.

BTW, I isolated the hiss to one of the ECC88’s in my preamp. Since I just put these back in, I’ll see if I should try to let these cook for a bit more before anything else.

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These are the adapters that I got.  There may be better, with these I had no complaints.

I got 2 ceramic gold plated socket and 1 with the Korea tin plated Korea socket.  I think the Korea may be a Belton socket.  I decided to try each in turn to see if there would be a difference in the sound.  There was.  When I had my CSP3 I had the gold plated in it and the tin plated in the UFO25.

Right now my system isn't set up so I don't know which I will end up using in the UFO25.

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No you're not crazy... mind you, some think that audiophiles are crazy 🤷‍♂️.  
There could be a number of reasons to explain what happened.  In some areas incoming power is affected at different times of the day and that can have an affect.

Once I had a similar experience and couldn't figure out what was going on until I noticed that the rectifier that I thought I had rolled in fact I didn't roll.  The original was still in place! 🙄🤦‍♂️ felt like a 🦍.

James, you had me at “I’m home”.  What a beautiful way to describe it! I can relate to it considering I took a 2-month hiatus from listening and what I am experiencing now is “I’m home and it looks damn sexy after the remodel’ (I hope I can also say that about the actual house once the on-going remodel concludes).

Thx—for clarifying that your comment was based on the other 300b amp.  With Sarah, I think I’m getting both (beauty and truth).

Love that you’re already tube rolling—-fantastic discussion from other members—-lots to learn from this thread!  I have for now decided to take things slow (I’ll share more in my thread).

Oh, can we have a picture of your new setup please?

This has been a very interesting day....and it isn't over yet.

I started out by going back to the 53KU rectifiers, which sounded really good. More air and more space, but slightly less bass compared to the GZ33. Then I added one of my favorite input tubes from the UFOs, RCA black plate 6CG7. For those unfamiliar, the 6CG7/6FQ7 tubes are 9 pin tubes with the electrical properties of a 6SN7. You can use them in place of a 6DJ8/6922/ECC88 without an adapter. They made the sound even better, but I figured I should try a 0D3 instead of a 0C3 in front and wow. With the bias switch at high the sound was just amazing. Huge sound stage, tons of detail, all the bass I could want (or expect from my 6 1/2" single driver speakers) and just the most living, liquid sound I've ever heard.

I could have stopped there, but the 6CG7 was so good there was another tube I wanted to try. I picked up some ECC40 tubes to try in my (non-Decware) 300B amp. They are an early attempt to miniaturize (i.e. make cheaper) the 6SN7 and they have a funky 8 pin English base. But you can get adapters for either a 6SN7 or 6DJ8/6922/ECC88. They were too warm and rich for the 300B amp, but I thought they would play well with the '25s and I wasn't disappointed. They sound like the 6CG7, but are more dynamic and with more bass. The sound stage is still huge left/right and up/down but has kinda collapsed front to back (which was never great in my room) so that is a bit of a downside. I'm not sure how these are going to play for the long run, but right now the sound is amazing.

Re: break in. For the last few days the sound has been very consistent on my '25s and (knock on wood) I feel like I'm through the weirdness. I'm not a patient person so I like to run new gear overnight to get it broken in faster. And when I do that with amps I run them pretty hard, both by playing them louder than I would ever listen (I play them into a dummy load and set the volume right below clipping) and also going with more aggressive material. IMO what new caps really need are transients, and harmonic complexity. I play a lot of big, modern orchestral music and I have a "burn in" track from an old Stereophile test CD that is a bunch of people pounding on pots, pans, drums and other noise makers plus electronically generated low and high frequencies that I run for a couple hours each night. I also have some Tibetan singing bowls albums that I would listen to when I needed to chill out after a bad day at work, but after Steve said they were good for breakin I mix them in too. To me they sound like tuning forks (pure tones) rather than something harmonically complex, but whatever. So I play the amps for 10 or so hours over night then turn them off for 3 or 4 hours in morning to cool off. This worked really well for my UFOs and it seems like I worked equally well for the '25s, but JMO/FWIW/YMMV and all that.

What I learned over my Thanksgiving Vacation:

• The UFO25s have amazing powers of resolution.

• The 53KU Rectifiers may not be right for the '25s after all.

• If the 7308 tubes don't sound good something else is wrong with my system.

• Even though the front VR tubes and bias switch have big impacts on the soundstage, you still need to move the speakers to get it right.

So, the long story short is I was a little frustrated that the 7308s didn't sound better than meh in the new amps. Maybe it isn't healthy to have an emotional attachment to vacuum tubes, but 7308s and I have been together for a long time, and they've sounded great wherever I used them. So I went through a ton of tubes, both in the '25s and my (non-Decware) preamp and ended up very close to where I started the whole journey:

Mullard GZ33 rectifiers.
Mullard EL822 power tubes, with adapters.
Amperex 7308 input tubes
Raytheon 0B3 in the back
Hytron JAN 0C3 in front.

The story has a happy ending because for the last couple days I've been listening to the biggest, most detailed, most dynamic, most intoxicatingly liquid sound I've ever heard. I need to get the preamp and the speaker placement just right for everything to finally lock in. Now all the other tubes are back in the caddy (for now) and I've stopped worrying about tweaking stuff. I'm just listening and it is a great place to be.

CAJames wrote on 11/28/23 at 00:26:53:


It's always great when the first dance ends and you can sit and talk. I've been in and out of that stage lately. These amps have so many potential worlds of sound within them.

CA,

I’m most interested in changes to your speaker placement.

What is your room size, and before the 25th’s speaker location, and after?

Toe in?

Love following the progress! Yours as well as Kamrans.

Best,

Geno

FWIW here is a picture of the room (and Nicholas) from another thread, when I still had my UFOs:



The open side is to my right, and to the left there is a fire place.

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Your room is also extensively treated, a situation in which I am unlikely to ever be.

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Yes, that is exactly what I'm doing. You don't need any changes to the stock amps to run balanced, you just need the custom XLR -> 2x RCA jumper. I had mine made by a seller on ebay.

As for a preamp, I'm using a Woo Audio WA22. It is also my headphone amp. For me personally I learned a long time ago I need a tube preamp in my system. It adds just a little bit of secret sauce to the sound, in addition to the convenience features.

If you pursue this I'm very interested in your experience.

So I've been re-listening to some of the recordings that sounded "beautiful, but maybe too beautiful" with my non-Decware 300B amp. And the differences between it and the UFO25s are both subtle and shocking. The overall "sound" is pretty similar, the big difference is the 300B had a little juicier low treble to high bass while the '25s have more high end sparkle. But the '25s are shockingly more dynamic.

I guess the word that I would use is sudden. Both loud and soft seem to jump out of the speakers. I knew the 300B transients were smoothed out a little, but I didn't expect anything like this. Its been almost a year since I was listening to my UFOs (with the anniversary mods, also balanced monos) but I'm pretty sure I never heard anything like this with them either. It is resolution like this that was the reason I wanted to upgrade to the UFO25s, and good on me because this is sound I've been looking for. Imaging in my room is never going to be great (although the '25s image better than anything else I've had) so the spatial illusion of "musicians in the room" is less than convincing. But the sound of musicians in the room is remarkably lifelike. Better than lifelike in a lot of cases because the recording was made in better acoustics than a lot of venues where I've addended concerts, or played or practiced myself back in the day.

Has it really been over a month since I posted in this thread? I've long ago stopped counting the hours but I'm sure I'm well over 500 hours on the amps. Before Christmas I did one more big tube tryout day, because there were tubes on my "list" that I still hadn't heard. What I settled on was a bit of a surprise.

Mullard PCC88 input
Mullard EL822s power
RCA 5R4GY, WWII, DD getters rectifier
Hytron 0C3 in front
Raytheon 0B3s in back

Neither the PCC88 or esp. the 5R4 was anything special on my UFOs, but on the '25s they have that goldilocks balance of speed, transparency and tube yumminess. Maybe just a little less speed and transparency compared to the 53KU, but the extra yumminess more than makes up for it. What they really do it highlight the tubes I have in my preamp, which I also feel like I have well sorted. So for the last several weeks I've been just listening everything sounds great. No promises, but I'm not planning on making any changes for a while.

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Yeah. The one thing I'm still temped to do is try more VR tubes, both front and back. But so far that just seems like "too much work."

Tony, that made me laugh!! Yeah, guilty... I just futzed. James got me curious again. I'd tried the 0B3's in the output VR position several months ago and determined it wasn't for me, but couldn't remember why. Sylvania 0B3's warming up in the amp as we speak.