Has anyone used the aesthetix calypso preamp?

Sounds like it does and has made you happy in the process which is all you can ask for. I am not that familiar with the First Sound (with only a short listen) nor the VAC for that matter. I do have a friend who used the First Sound for a little while. I have stayed more with main stream products that I can readily listen to and/or borrow(which is getting pretty dang slim.)
I always try to make sure everything is compatible that I purchase and it does require homework to succeed. The Ayre is an incredible match with the Calypso(in fact, the guys at Ayre even recommended it.)I'm sure they are friends with Jim White of Aesthetix since they (along with Charles Hansen) have joined forces at Theta for a few products in the past. All of these guys believe in using zero feedback designs. So, all of this falls in line with my belief of time aligned, phase coherent speakers and components that are zero feedback that offer good time domain performance.
I have listened to the ARC Reference Mk.II, the BAT 51se and a few others in my system. The Calypso easily held its own for less money(WAY LESS!) So, That pretty much sold me own it.

Has anyone used a VK 75se with a Calypso?

As a quick note. I have been trying the Calypso pre amp for a few months now. First off it has surpassed my Placette Active line stage in all ways. I have it hooked up to Plinius SA-102 amps at 47ohm input and have had no issues. I have found the stock Sovtek tubes to lack in dynamics, bass and extension. The Mullard anf Telefunken (sp) are great!!!!!!!

Jadem6....any possibilities of getting your hands on a Rhea Phono stage to check out that combo?

RWD

Mine is *Supposed* to be here Monday...i won't hold my breath.