I'm another happy Audio Mirror owner and would echo all positive attributes that Rockadanny already has elaborated on.
I bought mine about four years ago and had Vlad install Vcaps and balanced inputs as well as upgraded furutech IEC's. I was using them with Merlin's with great success. About that time I got the itch to try a different speakers....King Sound Prince II's. Unfortunately the AM's didn't have the wattage to run those speakers so I reluctantly sold them.
When I sold the prince II's a while back I got in touch with the gentleman I had sold the AM's to and asked if he would sell them back to me. He agreed and thus I have them back. Couldn't be happier with that good fortune.
A good friend of mine is a tube guru and suggested I try VT99's or 6f8g's as a substitute for the 6sn7's. These tubes need an adaptor which can be readily attained on eBay. I must say that this tube is a real winner. IMO it transformed my amps from very good to outstanding. Please keep in mind that I was using some pretty good 6sn7's already...Sylvania Bad Boys from 1952 and Tung Sol round plates from the mid 40's. Neither of these tubes can hold a candle to the VT99's. These tubes are a good pair of 6sn7's on steroids.
You might want to investigate trying those tubes at some point. They aren't as expensive as a good pair of 6sn7's. Mine are RCA's from the 40's. To be honest I couldn't go back to the 6sn7's.
I also appreciate the fact that these amps aren't heavy for a tube amp and have bulletproof packaging as well as being self biasing and will shut themselves down if overdriven.
They are a real hidden gem in the realm of SET amps.
All the best,
Scifi