Calypso Amplifier Matching - Krell?

I am seeking a new preamp and the Calypso is one on my list. I have read that there are potential impdenence matching issues with some power amps. I have read the measurements in Stereophile regarding some of this, but am a bit concerned that I may not be technically savvy enough to make the right determination.

To the point - I have a Krell FPB 200 that I have really enjoyed and want anybody's knowledge feedback as to the synergy between this preamp and this amp (FYI - speakers are Watt/Puppy and RA-Opus 21-GNSC CDP).

Also, impedence matching issues between the two?

Any ADDITIONAL comments on the pre over the above would be welcomed as well.

Thanks much in advance.
Guess nobody has an expierence between the two? I went ahead and ordered a Calypso and will post comments in due course as to the sound and any issues with the potential impedence matching.
I spoke with Musical Surroundings, the sales organization for Aesthetix and they confirmed with me that the Calypso has coupling capacitors at the output which protect against DC from going to your solid state amps. If you have a Krell, this means you do not need to activate the coupling capacitors within your krell amp to run the Aesthetix Calypso (and from what I understand, their other preamps as well).

Also, I spoke with Steve at MS (above) who runs his Aesthetix with a Krell FPB amp and he has reported excellent results and a great deal of satisfaction.

Sorry I only just came across your thread.

I normally use a Krell KRC HR with my FPB300c power amp in my system but a friend who has a Calypso lent this to me while he is on vacation and I used it with no problems at all with my FPB. The sound was excellent, warmer than the KRC with a richer mid bass balance though it can be argued that the Calypso does not have that last nth degree of crystalline clarity & resolution. On the other hand, the Calypso allows more midrange detail to come through than the KRC, especially on brighter recordings. The sound stage is less wide than with the KRC though this may be due to the fact that my friend's Calypso is using standard tubes.

Overall, I have to say I am tempted to get one though I am at present undecided yet.

And it is true the Capypso is capacitor coupled which will prevent any DC offset at its output.

Hope this helps.
Solntgreen, Thanks for your comments. I am a bit surprised that the sound stage was not as wide with the Calypso. I have read very positive comments on the sound staging ability of the Calypso.

I figured I would give up some "crystaline clafity" due to the tubes. I look forward to getting it this week and hooking it up next weekend.
I also read that the sound stage performance of the Calypso is excellent, though there were also comments in Calypso tube rolling threads that this only comes through with better tubes.

Havig said that, the KRC HR is no slouch on sound staging and in my system, its ability to better my friend's Calypso is clear. The time I had with the Calypso in my system also showed that the KRC has excellent soundstage depth, matching, possibly also bettering my friend's standard tubed Calypso in this area. This was interesting as depth was the only negative point mentioned against the KRC HR in Stereophile's review a few years ago.

But apart from sound staging, it has to be said that the Calypso's midrange and mid bass sound, and its warmer balance, especially with brighter recordings, is very appealing and I am still very tempted. Before deciding on this, I will try to arrange to hear a Calypso with better tubes.
Yes, I figured I would have to do some tube rolling with this unit to maximize performance. I typically like to run a new tubed unit at least a month before commencing with tube rolling to break in the unit and also familiarize myself with the standard tubes. I will do more work on learning of what tubes others are recommending and get some on order. I already have a decent stock of NOS 6922 family of tubes that I liked in my previous Kora Hermes DAC. My system is highly resolving, so typically I can get a pretty good feel for tube changes rather quickly.
Time for my report and experience with this preamp. Many have provided detailed reviews of this pream, with one particularly exceptional review and thread (if one is considering this preamp that thread should be reviewed).

I purchased my Calypso from a dealer earlier this year, it was manufactured in February 2007 and sat at the dealers during this period, partially as an in store demonstration unit.

The tubes that arrived with this unit were not the noisy, problematic tubes that many have commented on. The sound of this preamp with my Krell FPB 300C amplifier with the stock tubes was good to very good. Certainly it bettered all of the following: BAT VK5i, Cary SLP 2002, Krell HTS 7.1 which reportedly has a Krell KCT based preamp built in (though I am sure not to the full level of the KCT).

With the stock tubes, the Calypso had better control over the full frequency spectrum than all of the other units. The sound was more natural than the BAT and actually quieter as a whole. The depth, width and focus of the Calypso was also better. It had a more natural sound over the BAT and better control in the lower octaves.

Compared to the Cary, the Calypso again was much more natural sounding than the Cary's warmer presentation. The Cary conveyed a more "traditional" tube sound, a bit mushy. The soundstange with the Cary was always fairly good, but not as well focused as I would like. The Calypso stock was noticeably better than the Cary in my case, but the Cary is a good preamp for its used price and in the right systems.

Vs. the Krell HTS 7.1, the Calypso was noticeably warmer, actually a bit more natural to my ears. This is exactly what I was expecting. The sound is moderately different overall with a better staging capability. There is no doubt that I prefer the Calypso over the Krell HTS 7.1 as I suspected I would. But in the same breath, I still need to give credit to the HTS 7.1 for its excellent 2-channel preamp built-in as one of the best by far that I have heard mated into a pre-pro.

With upgraded NOS tubes, the Calypso truly arrives at a whole new plateau or level of performance. Having discussed tube experiences with others and reading many of the threads on this topic, I decided to go straight to what many consider the best tubes for this unit. That being the NOS matched Mullard M10 12AX7 tubes and a pair of the Philipps NOS 6922 tubes. Althought I have played around a bit with the 6922s (and the 6DJ8 counterparts).

The addition of the Mullards was dramatic in every sense of the sonic spectrum within my system. Better, more natural, transparent performance. Significant step up in staging in all facets. Beautiful, but not soft or mushy sounding, noticeably tubed performance.

Changing out the 6922 tubes with the Mullards in place has much less impact on the overall performance of this preamp. Slight, recognizeable, but a difference that I felt required some much more conscientious listening to recognize the changes (between various NOS tubes I tried).

Overall, my opinion is that if one is purchasing this preamp it is mandatory to change out the tubes and this should be factored into your budget. You can expect to pay upwards of $750 for the Mullard M10s. Quite a bit less for the 6922 tubes. I would not bother trying all sorts of lesser tubes as I suspect one will ultimately end up with the Mullards and be out the money of these other tubes. So in my opinion, such a purchase of one of these units must factor the cost of these tubes into the price.

I do not know how hard this preamp is on these main tubes (the 12 AX7s). I suspect they are pretty hard on them and not sure if these tubes really will last the rated 10,000 hours in this preamp. But even at half of this life, at 4 hours per day you are looking at over 3 years of life.

For the record and wanting to seek feedback on this tube life issue, I would appreciate others experience with the Mullard tubes in their Calypso. When I power up my Calypso with these tubes, the initial powering up causes these tubes to glow very bright for the first second and then they die back down to the regular anticipated glow. Has anybody else ever experienced this phenoma?

As a point of reference for my sysem to know what my analysis is based on:
Power amp: Krell FPB 300C
Source: Resolution Audio Opus 21 GNSC modded
Speakers: Wilson W/P 5.1
IC: Transparent from Pre to amp and Stealth from CDP to Pre
PC: Synergistic/Transparent
SC: Harmonic Technologies

Conclussion: I think this is a bargain priced preamp that with the upgraded tubes competes very well with the other preamps I was considering: Cary SLP 05, ARC 25/26 and Ref. 2, Ayre K1Xe and a few others. You will pay a fair amount more for the ARC upper end units (used) than the Calypso (new or used, with upgraded tubes) and I am not so sure the differences will be significant. I would ultimately like to get a Ref. 3, but cannot afford to do so at this time and likely for a couple of years (for me to justify the additional cost over the Calypso).

I do not know the improvements with the signature version of the Calypso, but have been told directly by them that the upgrade can be made to a standard Calypso. I will await word from more people having a chance to compare the two.

I highly recommend this preamplifier and consider it a very good deal (with upgraded tubes) based on the units that it competes very well with.
I spoke to aesthetix directly and he said that several clients FPB's ha failed while using the Calypso w/out coupling capacitors engaged. Dealers will tell you any thing to make a sale call the manufacturer for tech advice.