I recently dealt with Kevin looking for NOS tubes for my Melos monoblocks. Kevin took the time to explain alternatives. The tubes that I got from him made a significant improvement to my amps performance. I would highly recommend him.
Tubes & Audio Research Corp.
When Audio Research ships a set of tubes, they have them individually marked to match a certain area where they want you to install them. As long as they are the same type of tube does it make a difference which tube goes where? Are you better off buying replalcement tubes through Audio Research and pay 3 times the normal price for them for the testing they do?