RR, this is something I have been wondering as I wait for my Taboo. I saw your subsequent post about finding the right synergy between your Taboo and CSP2+, so I gather you decided not to try the Z-Stage? Perhaps I missed a post somewhere in which you explained your decision. If so, my regrets.

In any case, I am thinking of adding one of the three—Z-Stage, Z-Box, or CSP2+—to my eagerly anticipated Taboo. Whatever it is will be sitting downstream from my modded PS Audio. The Taboo will be driving Audez'e LCD-2 and Sennheiser HD800 cans.  In unbalanced mode, the PSA produces 2v of output, so one of these seems to make sense.

I know there has been lot of discussion here about the "overlap" of the three units, especially the Stage and the Box, and I am not trying to rehash all that, just seeking some thoughtful guidance. One thing I don't want to do is buy a lot more functionality that I simply won't use, e.g., the CSP2+. Personally, I am leaning toward the Z-Stage, for the benefit of added gain, with the minimal electronics to get it.

Congrats! I'm eager to hear your impressions.

I would try it out if I didn't have the CSP2 and the ZBox. And with these I can control four inputs (Sony SCD XA5400 ES, ZDAC-1 providing analog for my Sony BDP S2000ES and my DVR, and the analog out from my TV for streaming etc.) and still have a spare input on the Torii for occasional use. And it all sounds SO GOOD.

I predict you're going to be very happy with the ZSTAGE.

Well, that will be an amazing system. You may never leave the house. . . .

Looks like just the ticket for you multi-channel folk. Or at least until the price is published!

Huzzah! My ZSTAGE is on its way.

This just gets better and better. Last night, after extended listening, I decided the Mullard 12AT7 is too much. Like living on chocolate and Pinot Noir. Gotta pull it back once in a while for a little cleansing. There was some music, particularly with what I would call naturally rich bass—e.g., some of the Linn & HDTracks hi-res recordings in the jazz genre—that were too rich with the Mullard. I tried the JJ 12AU7 that ships with the ZSTAGE, and for whatever reason, it had some sibilance in it. So, I tried a modern Genalex Gold Lion 12AU7. It also had some sibilance in it, so I am thinking maybe they each needed some break-in [both new], but then I gave the Genalex a little "extra juice" from the ZSTAGE on the Bill Evans My Foolish Heart cut, and that cured whatever was going on. BTW, the HDTracks 192/24 release of Waltz With Debby is something special. The sound of brushes on snares with that bass is just extraordinary. And the sense of intimacy conveyed by the small background noises from the club is very engaging. On this kind of recording, Lucid mode is killer.

Interesting note: while Steve describes the 12AU7 as warmer and smoother than the 12AT7, with the T having a bit more gain, what I am hearing is that the Mullard T is also "fatter" in the lower registers. And flipping the bias switch was not enough of a diet. Right now, the Genalex U is sounding very nice, while the Mullard T is still in my Taboo.

Pale Ryder,

Sounds like you are having fun!

I think you are right about tube break in. Seems like each tube takes a while to really show its sound, especially some of the new production ones from Russia can take 75-100 hours if I am not crazy.

Also I find that each tube type has "family resemblance" but a notable range within that depending on the maker, year, build, materials etc. Especially in the Zstage, where one tube has a big impact on the sound of the system. Add the bias switch and gain nob, as you have experienced, the Zstage is powerful. The gain nob and how it changes the source output voltage alone is huge. So it is no wonder that a higher or lower gain tube in this circuit will make a mark.

If the Zstage is set close to unity gain for a given tube type, I find the extra gain of 12AT7s generally shows up as pushing a little harder throughout the range, tending toward a sound that is a bit more dynamic with slightly more defined "edges." Within that, the tonal characters of the specific tube is revealed with a bit more definition. Alternately, the lower gain of the 12AU7 (adjusted to relative unity gain in the Zstage) seems to generally be a bit more laid back across the range...less push with slightly softer definition. So if comparing a 12AT7 and a 12AU7 of very similar tonal character, and adjusted for unity, the slightly softer delivery of the 12AU7 could easily show up as slightly "warmer."

I think there is another factor at play here too though. If I read it correctly, the 12AT7, being more powerful to begin with, makes the Zstage more powerful, and thus causes the bias switch and gain nob to be a little less subtle than with a 12AU7.

Then there is synergy, or lack thereof with the rest of the stuff... the source, amp, the tubes in it, speakers, cables, room, setup, etc. I wonder...with two of the same Mullard 12AT7s in a row...seems like that could make that tube's signature, whatever it is, relatively dominant.

Just thinking that this simple Zstage thing can bring a lot of subtle and less subtle variation to the game....Makes playing around fun though, that is if you like that!

Also, your Zstage is very young, and if anything like mine, it will change for a while. I was just looking back at my notes and I see that I thought it was not fully burned in for four or five weeks! Another thing I noticed, was that for me, my enjoyment of different tubes was much more even after burn in. Makes sense that the internals of the Zstage that need burning in and the resulting tonal impacts would effect the signatures of different tubes in different ways. And that after burned in, the Zstage will sound more stable and more transparent.

Have fun with the new toy, and please keep us informed!