Ayre V3 owners. What preamp do you use?

The impedence mis-match you need to pay attention to is the preamp's OUTPUT impedence and the Ayre's input impedence. The Ayre, at 10K ohms, is definitely on the low side.You want a preamp with an output impedence of 1K ohms or less, as I understand these things. Try a Placette.

Not sure about the Modulus' output impedance spec, but 47K sounds wrong. Perhaps you're reading the INPUT Z spec? Output impedance of most preamps is typically much less, usually around 600, 500, maybe even as low as 50 ohms. Output Z is typically an issue when using longer interconnect cables.
The Ayre upgrades were (1) a reduction of gain from 30 dB to 27dB (high-gain tube preamp owners had a problem with excess amp gain as their volume pots had to be operated nearly minimized) (2) addition of the Ayre conditioner - an inductive filtered power supply. Mine initialy had only the 1st upgrade; the Conditioner was a definite enhancement.

Drubin and Bob budus- You are right... That was my mistake the output impedence is what I should have been concerned with and it is as Druvin had mentioned only 1.2K ohms. I've also spoken with the people at Ayre (Who are really GREAT they bother to spend the time with you!) who did not feel it was a mis-match at all. They actually thought it was a great combination. They also mentioned that the difference with the upgraded amp running single ended and the balanced configuration is not as big a difference as people make it out to be. They just recently came out with a burn in CD that they said makes a bigger difference that balanced vs single ended. Once again thanks for all your help. Best-Gary

I read somewhere that if your amp has all the upgrades, Ayre recommends eliminating the ground. You should probably call them and see if this is true. I don't remember where I read it.

Thanks Blbloom- I have the first upgrade and they recomend that you deleat the ground and reverse the polarity. I did both and it does make a difference.