I hate to resurrect such an old thread, but I have an S7i and have recently compared it to two of the best of today's DACs, the Ayre QX-5 Twenty and the PS Audio DirectStream with Huron software.
Of course both can play 24/192 and DSD, which the S7i obviously cannot.
But when it comes to Redbook CD and PCM sources, the Wadia still beats either.
Both of the newer pieces are brighter, to the point of being shrill on some recordings, but the big area in which the Wadia excels is space, or the presentation of it.
Sure guitars and such sound great on the two newer DACs, but through the Wadia they are presented with a palpable sense of space around each instrument, where there isn't just the sound of a guitar string, but rather the sense of a guitar string being played in a space.
I don't know if I'd advise anyone who didn't already own one to pick one up used, but I was ready to upgrade, and I think the Wadia's beauty has just sucked me back in.
The S7i is still a great front end, even today (I was keeping one for a second system but had to sell recently to fund an amp purchase).
I'm not sure the Ayre or the PS Audio represent anything near the state of the art atm. Certainly they have their fans, but for me, for example, the Ayre was good but never great. There are however units that surpassed the overall (depending on what you're looking for) performance of the S7i (even GNSC Statement) years ago (like the EMM Labs XDS1) but even they couldn't establish that foundation that the Wadias get so right - which is what you're describing. It wasn't until the EMM Labs TX2/DA2 that I found a digital front end that surpassed Wadia in all facets including that critical foundation.
Some excerpts from my review of the EMM Labs combo:
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I've historically been a Wadia fan because their players got the most important thing in music right – drive (in fact, I still have a Wadia S7i GNSC Statement CDP - Wadia's last CDP - that I intend to use in a secondary system once I get the space). Wadia's players have always been unparalleled in my experience in driving the music forward. Up until now, subsequent to the death of Wadia (what exists now has no relation to the original company), I have not heard any digital that has gotten that right since. When I replaced my Wadia 861se with the original XDS1, I sacrificed that drive for the significantly lower coloration, better and more open top end and midrange and the vastly greater resolution of the XDS1. But not having that drive always bothered me, and along with the mid-hall presentation of the XDS1 (I prefer being closer to the stage) and the good but I never felt quite right treble, I was never fully satisfied with that CDP, even in V2 guise.
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EMM Labs’ new reference digital combo has everything that one could ever want - resolution top to bottom that is generations beyond their single box CDP (which was not a slouch), highs that are smooth and accurate (violin is as smooth as it is in real life while cymbals have just the right amount of bite and definition), unlimited dynamic range and musicality without coloration that I can detect – plus the best aspects of Wadia - drive and solidity in the bass/fully developed foundation to the music.