Has anyone used the aesthetix calypso preamp?

I use the Calypso with a pair of Vandersteen 2Wq's and Vandersteen 3a Signatures. The Aesthetix is driving an Ayre V5x. This is by far and away the best sound I have ever had out of my system. The Calypso is a preamp that can be honestly compared to the best out there and you will not feel cheated! It truly is a great buy, well built and offers unbelievable sound. After listening to a lot of other "Expensive" preamps, I just can't recommend it high enough!

I was checking in the owners manual and there is actually no statement to the minimum impedance that can be used with this preamp. Bhouser brings up a good point with this. I think, however, that the 50k is refering to a balanced impedance into the amp since the Aesthetix pre is designed to be used for balanced ins and outs. It actually converts a single ended input to a true balanced circuit in the preamp. This would place a single ended impedance at 25k for the amp. (The single ended outs are converted from balanced also) I use the Ayre in balanced configuration which shows a 200k input impedance to the Calypso(100k on each leg.)
I would give Aesthetix a call and ask them.
I used an Audible Illusions L-2 that was rated for no less than a 20k input but Art ferris told me 10k was ok and it did not use a buffer circuit like the Calypso which should make it immune somewhat to impedance mismatches.

Well, Bhouser, my point is, I have not seen anything "Official" from Asthetix on this subject. As I stated, you would think mention of this would be in the owners manual if it was a problem. I plan on calling them tomorow and asking about this at which time I will post the information.
There are a lot of others factors that can cause reduced dynamics, etc. besides impedance mismatches between components such as input sensitivity of the amp versus output of the pre associated with input sources outputs. Normally, an impedance mismatch will cause a roll off in the highs and not so much affect dynamics. This roll off wouldn't be too bad but would exist. Most tube preamps like to see at least 20k.
I'm not trying to dismiss your concerns but the Calypso is a WELL designed preamp in every technical sense. I just can't believe a company manufacturing tube preamps would require a 50k impedance which seems awfully high.
On another note, I can't believe an output coupling transformer would increase dynamics. How exactly is it doing this because it is not all about impedance you know. I would think this would limit bandwidth and create other problems.

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.

Jim White has said that he didn't know where the 50k figure came from but the preamp would easily drive much, much lower impedance than that listed. He siad not to worry with most any impedance.