I may have been a bit hasty in my judgment of this old girl. When used as an amp only (no preamp) I was hard pressed to tell the difference between it and the amp on the Mac. It was clean, quiet, no hum, buzz or hiss. With the preamp in the loop the hiss level rose and the sound was noticeably less open. Of course, with the preamp in, all of the noisy pots and switches became an issue.