If u r going to consider older amps like the Lehmann, then consider the Meier Conda Opera. Excellent Meier amp, mates extremely well with the HD800 (in my opinion), many more features than the Concerto, and u can frequently buy it at a very reasonable price in the for sale section. The Concerto is suppose to be transparent where the Opera is transparent but slightly warm. IMO, the slight warmth of the Opera mates extremely well and give needed body to the HD800.
Edited by XLR1 - 5/30/10 at 1:57pm