This is a followup to an ancient thread, but FWIW, having owned a lot of Ayre gear, including using an Ayre K-3x preamp with first a VX5E and then a VX-5 (over a period of about a decade), I've now had an Aesthetix Janus Signature (linestage/phono stage) fronting my VX-5 for some years now, and I find that the Aesthetix/Ayre combo has been even more satisfying to me. But there are two caveats here - A) the comparison between the K-3x and Janus Signature is not a fully symmetrical one; perhaps the stock Janus would be a better comparison there; and B) the Janus has had issues with tube noise that I've satisfactorily resolved over time with careful tube selection, but it will never be as hassle-free (or have as low a noise floor) as an Ayre preamp. While the Aesthetix gear has a bit less high-end detail in comparison with the Ayre, I find it a bit tonally richer. But the Ayre gear is very fine gear indeed. And Charles Hansen and Jim White, the founder/owner of Aesthetix, did a bit of work together and were friends, and shared similar design philosophies- the gear has mated very well for me, and I see the house sounds falling just modestly on either side of a very neutral line, and of course also be dependent upon the balance of the rest of one's system.
One last point- the Aesthetix gear (and certain other tube gear) really goes even farther with good NOS tubes to suit one's personal tastes than when used with stock tubes, though it's not night and day to my ears, and of course it entails potentially substantial additional costs.