Hey Bilyeaux.

Though DACs and Pre's are clearly a vast arena of sonic variability and associated costs, I suspect your DAC/pre will just sound better with your UFO. So if you like what it does now, you will probably like it with your new amp.

As to the balanced option on the UFO2, if you feel like you can use the full gain addition from your DAC balanced outs, getting the built-in transformer setup might be great. It is not just balanced out you get, but it runs the signal through some good sounding transformers which clarify the resolution smoothly.

With my DAC, I don't prefer the in DAC volume even though it is supposed to be ultra transparent, so I run it wide open. And through the balanced outs, it runs 6 volts rather the 3 volts through the RCAs. I like the bolder/denser sound with more voltage, but not the full 6 volts here.

I am a real fan of gain adjustments, and I use a ZBIT, which is a separate component that is basically the same transformers, but with a variable gain, so you can tune the output voltage to tastes, and being its own component, it can be used with different amps if that ever happens.

This may or may not be an advantage depending on preferences. Adding a pair of RCAs in the blend, a gain pot, and requiring another pair of  ICs, it does add stuff in the signal path compared to having the non-gain adjustable transformers built in.

But for me, I am glad to have the gain adjustment for tuning gains between components for the best sound. I do "gain riding," where you can keep the same volume while turning up the ZBIT and down the amp, or visa versa, changing the character of the signal with more or less voltage from the ZBIT. More ZBIT voltage makes the sound bigger, more powerful, dynamic, present, weighty etc, and less calms all these areas....I really like this for fine tuning the system gains together, and for adjusting for different recordings styles, able to beef up a lean recording some, and tone down and open darker/thicker ones.

But it sounds like the volume adjustment on your DAC remote is important to you. In this case, gain riding may not be your thing, having to manually adjust things. The ZBIT then might or might not an advantage to you for tuning the average system sound. I never use my ZBIT wide open, finding the full voltage from the DAC through it to be too much. Generally I run it in the 2 o'clock to maybe a little less than 4:30 for my system, but I think some might run it wide open.

Hopefully others will comment. And it might be a thing to talk with Steve about if you talk. There are a number of Decware components with this same non-gain adjustable option out there, and it might be just fine for you.

Hope this helps some,

Will

Guessing you have checked this out, but if not, the first question might be: what is the real efficiency of your particular Heresys after any upgrades you might have? This might make the SE84 versus Rachel a more, or less important choice. Whether an amp is loud enough for you would depend on speaker efficiency, room size, how far you are from your speakers, listening preferences and sometimes more. If you feel on the edge power-wise, you said you liked loud, but measured dBs from your listening seat, though not perfect, would give a clearer frame of reference as to how loud loud is. And if you don't have a meter, you can get pretty nice ones for smart phones with some research. Also, you may have come across them, but there seem to be more and more threads these days about "pairing" different speakers (speaker efficiencies) with Decware amps that you might find interesting. Even if they are not referencing your speakers specifically, these might give some insights into matching lower power amps with everything else and expected effects.

As to the DAC sounding better, if your new amp sounds better, yours being a current DAC by a company a lot of pretty serious listeners like, your DAC will likely sound better. I can't be positive,  but my guess is that this is likely a case where a more resolving and liquid presentation from the amp, will let the DAC do its thing better, more than showing problems with the DAC.

Personally I can't answer the DAC pre versus ZBIT or other Decware pre stage without trying it. But it brings up a few considerations.

Checking this on my DAC, perhaps with a different gain design, I hear pretty subtle differences in musical attributes from riding its gain with my Torii gain. Maybe a little, but negligible with a quick test. The main thing I hear is that it does not sound quite as good to me (in this very resolving system/room). So guessing it is designed to not change the character of the sound at different gain levels. Whereas, riding the ZBIT with the Torii makes notable differences in signal intensity and associated dynamics, weight, clarity, etc. And the CSP3 makes more than the ZBIT, the CSP3 having much more of a voltage range. The CSP3 being a lot like an OTL amp made as a preamp (Output TransformerLess using tubes as the output instead of transformers), it imparts a bigger dose of its tube and design qualities on the sound as well as loads of voltage potential.

So I am sorry, I can't answer your question about DAC gain riding, and hope others who have experience with the "Gain Cell" can help. But I would imagine it might be designed as a transparent volume to give a similar sound from the DAC at different volumes. And if you can't easily figure this out to your satisfaction, you could try it once your amp comes, and see if it works, then consider adding a ZBIT and/or CSP3 later.

Another consideration in this would go back to my first comment here. If your amp is close to maxed out in your room, cutting the gain from the DAC might quickly kill any headroom you have. Alternately let's look at a high gain CSP3 between DAC and amp. Assuming your DAC voltage out matches or exceeds the recommended voltage for your amp inputs, the CSP3 would not make your amp notably louder per se, the amp maxing out at a given level anyway before distortion. But you would not loose anything, and the CSP3 would add its tube and other design character, with liquid gain riding clarity, tonal, dynamics, weight and density tuning.... The CSP's sonic contributions/characters being imparted using gain balancing between amp and CSP3, you can variably adjust the qualities of the sound you do have from your amp with the sonic characters of the CSP3.

The ZBIT would not be the same, but similar. Being simpler in design, having no tubes, and not adding voltage itself like the CSP3 can, its max voltage being the same as your DAC balanced-out voltage. But balanced typically creates more output voltage than that from the RCAs out. So the upper parts of the ZBIT gain range would be higher voltage than the RCAs, adding more signal power from the DAC, and that signal intensity being adjustable with the ZBIT. So it gives the things many of us like about having adjustable voltage. Associated, the ZBIT transformers do more than allowing higher gain from the DAC. As the signal goes through them, they sound like they do something, not just alike, but "tube-like" to me. They seem to clarify and articulate the signal with smoothness, giving a greater sense of musical resolution and density. So to me, it is more than just a way to get more voltage into the amp, and a gain adjustment.

I think the XLR inputs on the SE84 would offer the latter traits from the transformers like the ZBIT's, but without direct gain adjustment on the transformers... This is not just the same as a ZBIT, not being a separate component, so having less to run the signal through, but I think it would be more-or-less like a ZBIT on full gain, which could be nice also.

I hope this helps!

Will

Will, sorry for the slow get back. Great info, had to read a few times to get  a good feel.
Heresy's did not change according to Crites 98db
These are my brothers speakers I inherited and could not part with them.
Room is 14.6 x 14.10 x 10avg, I know a square......
Typically listen up to about 85 AVG db on my Iphone app.
Jazz mostly, new and classic, blues, classical, rock in that order.
From all I've read most remarks are that UFO2 would be enough power. And if my PRE-DAC is good then all good! If not then CSP3 likely next step. I will first break in amp direct to source, then experiment.

Thanks for the time and effort in your responses!

Bilyeaux