Dave, VA7DG wrote: "...what is the most popular interface being used between the PRO III and a tube amp? ( e.g.. Alpha 76PA )" ======== I use a Sultantronics ( http://www.sultantronics.com ) model LVP relay saver between my PRO III and Alpha 76CA. It's solid state (no relays), works flawlessly, and is cheap insurance ($24.95 USD). 73, de Earl, K6SE