This is dumb question and I'll be the first to admit it...

A receiver's or preamp's volume attenuator essentially restricts power flow (at least that's how I understand it from past threads), right? So when a receiver is showing "-db" which gradually increases to "0db" is it showing you the reduction in resistance? What does it mean when you go to the positive db's (i.e. +5db)? If you're running an external amp does that mean the preamp's internal amps are pushing extra power above and beyond the amp's? What about when there is no external amp?

I've never been able to figure this out. Some say that "0db" is reference level, but that's ridiculous because unless the darn thing had a built-in mic and autocalibration (like Pioneer now has) it would never know due to differences in speaker efficiencies. The only thing I can figure is that it's completely arbitary and different with every manufacturer, which is completely inane but just about right for the world of audio

Any ideas?