Ayre MR-X monoblocks - how good are they??

Sorry to take this thread somewhat off course but I did briefly want to address two comments: 1)"the Isis is not known to be musical." I am not really sure what exactly that means or whether it is intended to be negative in nature; however, based on my listening, the Isis are accurate, "garbage in, garbage out". They can be very musically natural when driven with the proper amp. By the way, I do not own the Isis nor am I in the market for new speakers. 2) "the Einstein is not very kind or musical on normal recordings." Again, I am unsure what "normal recordings" means and whether this is intended as criticism. In this particular instance, I do own the Einstein phono stage and while it does have weaknesses, it is accurate and does not sugar coat what is played through it. Normal recordings can sound spectacular with warmth and body, but again "garbage in, garbage out". My only point is that someone developing a system must make certain choices based on their perceptions and what they want to achieve. Accurate seems like a good starting point. Whether it is the final destination is another question. Note that I have no qualms with someone who chooses one of the other phono stages which are mentioned as each does have its strengths and weaknesses.

Semi:

Point taken, I think that what I really should have said is musically enjoyable. Again, the associated amp and cabling can make quite a difference in the final sound.

I am using the single ended Einstein and understand that the balanced version is even better.

With respect to the Einstein preamp, it is in my opinion a real sleeper. Although it has 18 tubes, 8 of those (6922's) are not really critical to the final sound which means that no tube rolling is required for those 8. Likewise only 11 tubes are "on" at any given time, the 8 previously mentioned, a 12AU7 and two 6922's associated with the particular input to which you are listening. The two 6922's which are used as inputs for each source and the ubiquitous 12AU7 which is always on have a major impact on the sound and tube rolling is highly recommended. To me this allows a certain tailoring of the sound of each input to get the tonal mix which you desire. In general, NOS tubes sound the best, particularly the more expensive Siemens and Telefunkens fron the 1960's. Mullards of the same vintage can also be nice. The unit is sensitive to power cords, AC filtering and to mechanical isolation. The aftermarket footer sold by Acapella works well. With respect to the JC-1's and the Acapella's, what can I say that you have not already heard? The Acapella's are a more difficult load that the sensitivity would suggest, likewise the JC-1's are a much better amp than people generally give them credit for but are not perfect. I have ordered a pair of Audio Note Kegons (balanced) and think that they will be my choice for a long while but only time will tell. The combination of the Einstein phonostage and preamp are synergistic and sound very good, certainly worth an audition.