Ayre V-5xe best tube pre-amp to match with?


I own an Ayre V-5xe power amp and strongly consider a very good tube pre - or the matching K-5xe pre amp from Ayre. Any suggestions?
frankpiet
Just heard Hovland HP-100, Nagra PL-L and Aesthetix Calypso (have heard all before but never against each other in one system except of the latter one). Hovland (less dynamic and less resolution and tightness than the others but a midrange to die for). Nagra to analytical but extremely tight bass, great micro / macro dynamics and air around Instruments, tons of details - but surprisingly quite uninvolving. Calypso despite the glowing reviews quite flat and noisy (probably stock tubes were not burned in, but great ergonomics and nice to look at). I´m very keen to listen to CAT SL-1, Ayre K-1x and BAT VK-31 SE.
Keithr:
would you though say that the VK-31 SE is a bad product? The two other remaining products on my short list are Aesthetix Calypso and Ayre K-5xe.
Having owned the 31SE for 2 years, and heard the Calypso many times in my system and the system of its owner, and both compared directly to the Callisto Signature which I now own, the 31SE is a mighty fine product. If you want to stay in the $3000-3500 range, you need to hear the 31SE vs. the Calypso for yourself. Going by anyone's else's opinion on what is "best" is likely to leave you wondering forever if you did the "right" thing.

Compared to the Calypso, the 31SE's strengths are its portrayal of space and decays. Compared to the 31SE, the Calypso's strengths are its low-level resolution and coverage in the trebles. Both do a good job in the coverage of the frequencies. The Callisto Signature significantly destroys both of these to convey all of these strengths in a "great" way, not simply "good".

I have wanted to know how the 51SE and many others have stacked up to the Callisto Sig, but the only thing that will likely me let this magical piece go is to find a full-function preamp to make life easier than the multiple chassis Io/Callisto combination.

John