Ayre V3 owners. What preamp do you use?

Presently running with McCormack TLC-1 Deluxe. Nicely transparent esp. in passive mode. Auditioned a Golden Tube SEP2 which had a better stage & was rather euphonic too, but I didn't buy it as I found out that they've gone under (no warranty or support). I'm now considering trying out a B.A.T., which I suspect may matchup quite well considering it's tubed & balanced. Is anyone else using this setup?

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.

Gold: if they'll still do the upgrade & you want to keep your amp then get it done soon. As you may know they've discontinued the V3 because it became too expensive to build anymore even after the 2 price increases. I still use a Chang power conditioner & an upgrade AC cord even with the "Ayre conditioner" which was the better of the two upgrades.