Elevick I never knew the Dynaco ST-80 was that quiet; I had a ST-120 way back in the early 70s. The reason I am asking this question is that I am running a pair of modified Klipsch KLF-20s in a second system and, as Raqual has pointed out, the more efficient the speaker the more the amplifier noise comes through. Speaking of Dynaco I had a ST-70 at one time with the Sutherland front end board and it was dead quiet; on the other hand the stock amp with the 7199s was pretty noisy. Thanks everyone for your input; I've learned a great deal.