What's the output impedance specification of the Calypso?
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If that's the case, then I can't think of any SS that wouldn't work.
However, many tube preamps have relatively high output impedance specs that make them poor matches with anything below 20k, so while Jim says the Calypso will work with just about anything, I'm hesitant without knowing the actual output impedance specification.
There's a used BEL 1001 MK V in your price range listed now.
If you are driving speakers with substantial swings in their impedance curve, you're going to want a SS amp that doubles power as impedance is halved.
Those are pretty good nominal output impedance specifications, but nominal output impedance can be misleading.
Check the measurements section of the Stereophile review and see if Atkinson mentions significant rises in the output impedance into lower loads. This is a characteristic of tube preamps. He would have mentioned this if he observed it, and if so, it would suggest possible bass roll-off if used with low impedance SS amps (say below 20k-25k). Atkinson will often be specific about this match.
Here is an old thread. http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1141898495&read&keyw&zzaesthetix In it it is claimed that Jim at Aesthetix at one time did use Ayre equipment in conjunction with his own. There is an old thread about a compatibility problem with some of the older stuff, and then Charles Hansen (Ayre) chimes in and explains an old bug that has been eliminated. Anyway Ayre might end up on your short list, in which case this old thread may prove useful.
I participated in the old thread mentioned above by Mmike84. I can still say without hesitation that the Ayre amps are a great match with the Calypso. No more hum issues unless you happen on a older V5.
I can also say with a certainty that the Theta Dreadnaught I is a great match also (2 channel and hard to find.) It offers a little more power and a bigger bottom. If there is a weakness to the V5xe(if you want to call it that), it is that the bottom octave is a touch light. Imaging and depth is its strong suit.
The Ayre and Theta's are some of the best amps around for use with Vandersteen speakers if you want SS. Since I use Vandersteen's exclusively, I cannot speak to other speakers.
The sound of no negative feedback amps with time aligned speakers makes for one heck of a sonic presentation.
I really want to give Jim White's Atlas power amp a run since it falls into this camp also. May never happen though!
Not true Russb. Here is the quote from JA's "Measurements" section of the Calypso review.
"The balanced output impedance was 112 ohms at 1kHz and above, this increasing to 3900 ohms at 20Hz due to the finite physical size of the output coupling capacitors. The unbalanced output impedance was a high 2400 ohms at midrange and high frequencies, rising slightly to 3150 ohms at 20Hz. In unbalanced mode, the Calypso will need to be used with a power amplifier offering an input impedance of at least 30k ohms if the bass is not to sound lean."
The trouble with many tubed preamps is the output capacitor size is limited which results in an increase in output impedance at low frequencies. Based on my experience, I would recommend a ratio of at least 20:1 of the amp input impedance to the (maximum) preamp output impedance. However, if you do not have full range speakers, or are not concerned with a low bass roll-off then maybe this would not be an issue for you. I will say the Calypso did not do much for me when run into a McCormack DNA 500 (input impedance of 10K ohms).
Bob reynolds; the 40K assumes you subscribe to the 10:1 minimum ratio camp, and would probably be fine in many cases. However, after trying a whole bunch of preamps, I have found better luck when the ratio is higher. One can review the potential effect for their own specific equipment by looking at the dBr vs. frequency plot and interpolating for their own given amplifier load. The 3,900 ohm reading is at 20hz, so one might find a small drop in output at low frequencies is acceptable, especially if they are using monitor speakers, or speakers without much output below 35-40hz, since the drop at the speaker's low output limit frequency may be smaller than the drop at 20hz. Personally, if I were to use the Calypso with a SS amp, I would try to get something in the 80-100K ohm input impedance range, such as the JC1 monos which I believe have 100K ohm input inpedance. Ultimately, the main reason I sold my DNA500 was to be able to try a wider variety of tubed preamps without being handicapped by the 10K ohm input impedance.