Yes the Treasures sound quite interesting!
JD...System/room and all....but from your description, my guess is that you can get more out of the Psvane 5881. At least here, they are very detailed and textured, possibly contributing the occasional sense of "sterile" you mention. But fully burned in, here, they are not lacking in bloom....rather being rich, warm and euphonic, integrating the complex detail and texture quite well for the most part...For my personal tastes, I tend to like a little more “invisibility,” less color, but every time I put these tubes in I am seduced by their tastefully portrayed, unusually rich and atmospheric qualities. Mine have plenty of hours on them though...at least 400-500. Could be our setups though!
I thought of this tube considering Sonicseeker's more linear amp than ours, and open baffles, both likely causing a more linear sound, likely leaner with less bass than the big Torii design creates. And comparing tube to tube, these could possibly fit Seeker's particular wishlist.
My MKIV is pretty seriously refined from original from the power supply/signal path work I have done to it and the CSP3, making them tonally richer, and more linear and revealing...and this in the already revealing setup I had. But it still has that MKIV bigness (excess bass to me if unadjusted with room and EQ in my case) and I suspect the ultra linear Jr is a bit leaner/less bassy still, especially with open baffles.
Another thing I consider in looking at tubes, I have done no tuning as I test these tubes in order to get real comparisons. Only volume matching with the Torii volume, my most transparent way to adjust to hear different tubes as accurately as I can. But practically speaking, in real use, between gain riding with the CSP3, CSP and Torii adjustments (including tubes), and EQ, I could solve issues with any of these tubes. I would still like only one or two of them most though!
My tubes now are:
Torii MKIV: Philips/Mazda GZ34, cryo’d Sylvania OB3s, Euro 75C1s (OC2 equivalent), and IEC/Mullard labelled ECC88 that look and sound just like late 50s/early 60s Siemens ECC88s, and RCA and Sylvania 807s.
CSP3: Philips/Mullard GZ32, 60s Mullard E88CC with parasol getters, and for input, a 60s Mullard A frame ECC88.
This creates an extended, open, fast, textured, revealing sound here cradled in pleasant but not intense warmth. Revealing and linear top to bottom with everything feeling real is critical to me.
With Sonicseeker's wish to shift the balance lower from the Tungsol EL34B....more bass, body, wetness, and texture, and without losing detail...in my room, the 5881 definitely shifts things to more linear, creating greater bass presence while being warmer, wetter, with more body ("meat"), and with amazing texture and detail.
The question becomes, does its particular balance appeal? The 5881s exceptional sense of detail and texture, within a warm/deep foundation, in a system that is very revealing and needing low end enhancement….depending on everything else, it could be too much, or just awesome. Being slightly over-colored by my tastes and room….like I said, they still get me. All that deep/warm/sweet sound, lucid enough to cause no soundstage degradation...its strange intensity...tasteful euphonic qualities in a great ambient stage...to me it can be quite magical.
They push limits, making them a tricky tube, but when we get right down to it...what makes the perfect power tube depends on everything else, especially with folks like us who have quite demanding tastes in how our systems come together. So we research the sound, pick ones that appeal to where we think we want things to go, and end up with a good selection to play with!!!
The making of a tube head!
The Tungsol 6L6G fits the wish-list in most ways, balancing deeper, warmer, more linear and dynamic than the EL34B with more body and bass presence. I really like the tasteful "big tube" sound of it...linear, tonal density, and clear ambient spaciousness with very nice detail balance. But here it does not increase texture much...a little, but similar to the EL34B...and it reduces high end detail just a little. Regardless, it is nicely balanced here.
Then some KT66s are similar in balance and character to the 6L6G, but go further...warmer/thicker in general...relatively "big tube," sounding still, powerful feeling, and clear. But based on the wish-list, and the EL34B being close, I am thinking these are not quite right, possibly a little big/bold, and some of them, darker/slower in parts of the balance.
JJ KT77s may be right, similar mids and highs of the EL34B, but more dynamic, more body, and notably more bass presence that is tight and big. They are quite exceptional at solid bass here, with pleasant warmth and good body. With more texture than the EL34B, they have excellent spaciousness and ambient sweetness, exceptional subtle and inner detail...I did notice a little upper-mid sizzle on just a few tunes that concerns me some.
That said, they reveal horns in a natural way similar to better EL34s. They have really good tonal density, but with complexity feathering body and edges, solving hard/focussed type of density for the most part. I tried a quad mixing an old pair of Genalex KT77 together with JJs in front, the Genalex were my preferred tube in my SE34. Though the Genalex were more open and articulate, the JJs, with quite good fine detail, seem more forgiving and warm. Still with plenty of detailed spaciousness, in this case a good thing. It made me wish I had a quad of Genalex to check out though.
Oddly, it may well be more what I am used to, but every time I put in the JJs, I am sucked in and impressed with their musical power, the bass and inner detail being especially amazing...but somehow I want something more from them without knowing what...Probably just preferences, habit and system/room, but perhaps also indicating things felt in perception, but not yet known. Can't say without using them more, but a compelling tube!
JJ 6CA7s, also tighter bass and more linear sense of balance than EL34Bs, with their sort of warm but open “big tubey” sound, and without losing the hazen mod...pretty great potential too. But again, at the moment I have more preferred flavors. Though I used this tube a lot for a long time, it is not pulling me in totally just now, with this setup. If the balance of the Chinese 6CA7s are similar or better, and with JDs report of excellent resolution and texture, seems the Treasure could suck me in....keeping the EL34 vibe but with more bass, body, resolution and texture.
I asked about the bass JD, wondering how they might fit in Sonic Seeker's wishlist. The Treasures sound quite tempting, and relatively inexpensive compared to earlier prices, especially now that Genalex KT66 and KT77, and Tungsol 6L6Gs have gotten more expensive.
I recall the early Treasures taking 300+ hours according to pretty reliable sources. This is believable to me, my Genalex KT66, sounding good after 100-150, but having taken something like 250-300 to fully come out.
Please keep us informed!
For me, 807s have the most natural sound of the tubes I have...quite linear, shifting the balance downward with more dynamic speed and body than EL34s, and with complex detail in space that is very good! They have more complex detail and nuanced textures than either Tungsol. This is not to say the Tungsols don't have the information. I think they have ver good detail, they just express it in a more consolidated, integrated way.
Here, I guess I could say the 807 detail quality and complexity is quite complete in a more textured way, though not in the face. Though less obvious than the 6L6G, they have excellent natural feeling dynamics. Being more complex throughout, with impressive micro dynamics and micro detail, they give a great sense of resolution and space...more fine particles resolving tonal density in a subtly textured and fast way...
The Tungsol 6L6G is in a similar neighborhood overall, but the 807's complexity, combined with less macro dynamics, its body is less concentrated. I guess it sounds like a blend of an EL34 and 6L6G or KT66...more linear, dynamic and deep than an EL34, and with a bit less macro dynamics than the 6L6G. The way detail complexity softens edges is more similar to good EL34s and to the Psvane 5881 here.
Here I find 807s relatively “invisible” overall, but impressive enough to be compelling. But I am "conditioned to them," having been "my new love" for 9-10 months now, a long time for a power tube here!
I could go on, but I am even confusing myself!!!