well had this amp playing for about 8 hour's. listened to several c.d.'s,norah jones, dire straits, holst steely dan, peter green, john prine's new c.d.,score from the THIN RED LINE,YES, ac/dc, mahler sympony #2, and it did not falter in anyway, just wish i knew a little more about this amp being i am fairly new to tube's and there topology. the tube compliment is 4 el 84's and 12ax7's x 2