FYI: There are two models of that QS. The older one uses 12AX7 tubes and the newer one uses 12AT7 tubes. Are you sure that the one you have is the newer one? BTW, the new model has no mono switch!
You must have a verified phone number and physical address in order to post in the Audiogon Forums. Please return to Audiogon.com and complete this step. If you have any questions please contact Support.