Richard,
For amp work I try to keep good notes, and was pretty successful for a couple of years. But as time passed, used to the sounds of preferred parts, I kept up for the most part, but got more slack. For ICs I tend to keep ones I really like for reference, while refining others. And with the rest, like tubes, feet, power, power cables... I have a pretty good memory for how they all sound, but the magic is so much about synergy, I still love to explore combinations of known things every so often.
As to front ends, not to confuse things, but have you researched ladder DACs? A few friends who have long had access to really good analog references found the Holo DAC to be naturally musical. Kitsune HiFi is the US rep if you are interested in checking the latest versions out. Also I guess you have checked out Denefrips? Holo was hot in serious listener circles, and may still be, and it seems Denefrips gets a lot of air play these days. I have not heard either myself, but they sound interesting. Getting the fragile and fine stuff seems to be a lot about excellent timing and it seems good ladder DACs can be good at this.
Also, not sure how deep you have gotten into computer hardware and power, USB cables, USB convertors, computer OSs, and software players and settings..... but to me, collectively, these make about as much difference as a good DAC for music that is revealing, complex, and smooth without smearing. If the computer is putting out a rough signal that truncates the very fine information, it is just is gone..... Along these lines, I wonder that a lot of developers may not have fully explored these important aspects of a front end. And if not, they may not have heard the potential of revealing nuances of inner detail, edge complexity, harmonic complexity, ambient information.... so these critical "real making" aspects of sound may not be there fully in a lot of DACs.... As bad, if designers think you have to mask or "warm" aspects of the sound to solve deeper digital resolution problems, to me these "artifacts" can be about as bad as those they are trying to fix. And finally, if they are not expecting to be able to get the very fine stuff musically, then this lowers the reference standard for user expectations and possibilities. I feel pretty sure much of anti "digital" bias comes from these sorts of issues.
I guess I was lucky to get in with some folks who did not let conditioned biases get in the way of seeking to pull the most from digital. With a lot of help from Eric Hider, the Tranquility DAC developer, and a lot of experimenting, ideas of "digital," or "analog" don't really occur to me. I have heard "digital," it has just been a long time since it has been a notable issue.
The early 60s Siemens E88CCs I have look very close in construction to the ECC-88/189s I described above except with gold pins. And they sound like family, but pretty different to me. In some ways they are so well balanced, articulate and clear they can seem a little technical (though they do have some complexity within that). Here, in the right mix, this can be good, but it is more of a mixer tube for me. The particular ECCs I mentioned are gentler so less tight and defined. And less pushed, they seem more rich in complex fine detail, textures, harmonics and complex ambient space.
To check my memory, I put the Siemens E88CCs in the power position of the CSP3. Compared to the warmish but well defined and detailed Mullard E88CCs (parasol getters) I usually have there, the Siemens relative lack of warmth and more up front clarity was a little shocking at first. Tending toward a little hard, but bringing out space very nicely, I started rolling rectifiers and ended up with a compelling sound.
I most often use old mesh plate RGN1064 or AZ11 globes in the CSP3 (4 volt/±1 amp and needing resistor and pin adjusted adapters). These tubes are calmer power-wise, and less dense than our usual 5 volt/higher amperage selections, tending more toward ease, space, fine detail, texture and generally, pretty subtle warmth I like. An unusual move for me, I put in a rectifier that I once loved for its slightly warm clarity and speed, a Chatham 5R4GWY. Becoming a little veiled as everything else improved I had stopped using it. A "potato masher" style tube, I think they seem pretty heavily damped comparatively, and this was likely what caused it to sound a bit veiled to me as my system became better at musically resolving fine detail and space. But with the very clean Siemens, though the Chatham made the whole fuller, less resolving, a bit slower and softer, I was able to punch up the pre stages a bit, bringing out lucidity and dynamics, and it sounds pretty good on first impressions.
This reduction in resolution made me think of too much "micro detail." I am wondering if what I call fine detail is more micro than "micro detail," being fine enough "particles" to fill in micro detail spaces that can cause it to feel like excessive detail? I am thinking "fine detail," when there is enough, brings out complexity and completeness, potentially resolving a sense of overly "detailed." In this context, though I can imagine too much "micro detail," I am wondering if I can have too much of what I call fine detail...the fragile stuff a lot of digital front ends, or tubes, or cables, or amps or whatever can easily harden and/or not fully reveal.
I think I get what you are saying about 3 as opposed to 5 tube positions with our amps. And compared to the Taboo, the Torii does have a lot of choices for power tube sound, as well as two pair of VRs for filtering the input and output tube's power. So I imagine I do have more complex tuning abilities, but I think all are equally powerful in terms of influencing the sound, so with three more tube positions in the CSP3, it can be a labyrinth. But I tend to come up with standards in given positions and play from there. For example, I mostly keep in OB3 VRs for my power tube filters, and 75C1 VRs for my input filters. I might play with those now and then, or adjust with different OB3s for a subtle change, but I almost always come back to this combination after playing with other VRs. And they really do have a powerful influence since they define the foundation of power to the signal tubes. Less voltage drop from the VR pushes the inputs and power tubes more, and more voltage drop, relaxes them more. And though I do tend to roll through inputs or power tubes individually now and then, all else the same, I usually end up back within a certain range of choices there too.
All else close, the CSP3 is a favorite place for fine-tuning to me, a tube change there pretty easily adjusting the whole system sound. I might just roll through a bunch of rectifiers pretty much knowing what to expect from each, but the magic one in the overall mix takes trial an error for me. And if something is interesting and almost there, then I might try another position in the CSP3 or in the Torii to pull in the whole, usually without changing other tubes.
I do have tubes that are too open mids and top, some too forceful in general for me, some too soft down low, some veiled, some with the detail tending toward rigid..... But for those tubes that balance pretty well on their own, when put into a well balanced set of tubes, I am not sure I have run across a tube with too much of what I refer to as "fine detail."
It is so tricky to talk about these things, each specific tube having a sound range in various settings. But tubes do have characteristics when compared to other tubes....pretty useful as pointers I think. And a tube that sounds great from opening up the sound in one tube set can make another set hardish, so I generally gravitate toward tubes that are at least close to the balance I love on their own. But since anything in a component or system can contribute to, or cause truncation, accent and/or create hardness or muddle, color the sound excessively.... I tend to like all system parts to balance pretty well on their own for the most part. That said, as they are in my system now, these over clean Siemens together with the under clean 5R4WYG create a pretty good balance. The Chatham is probably a little lacking in full resolution for my tastes, so I suspect it may not last...but a good sound so far, and an interesting test.
Also, there is no doubt for me, that having two pretty transparent pre stages to help balance system sound, and the sound across many recordings styles, is a powerful tool. Also nice for balancing tone, dynamics and lucidity with tube changes as my Siemens/Chatham experiment indicated.
But even with the best tuning, I find there is a threshold for the ZBIT and CSP3 where too high on the attenuator will harden and overstate the sound, and too little, will reduce dynamics, body, and lucidity too much. For me, having two stages helps make both have a fairly wide working range though, which can be useful. I often will tune one lower, and the other higher, or visa versa to get the best sound for a recording. The ways each effect tone and sonic character, complimentary but different, are pretty useful. The CSP3 (the way I have it tuned) is quite transparent, but also has a lot of rich tube lucidity and complexity. And the Zbit is musically transparent, but with a simpler sonic character. I am glad to have both to help find a good balance. As I think of it, I have been "gain riding" so long, I probably lose track of how powerful a tool it can be...balancing the pres together with the amp a big deal for the baseline sound of my system, and an equally big deal, I love how easily that base can be adjusted for tuning different recordings.
Shew, a lot of territory...I am tired.