What can cause different amps to sound so drastically different in terms of volume? For comparison, I was using a '65 Fender Deluxe Reverb (22 watts) in 100% original condition, a Marshall 18-watt (original) and a Dr. Z Maz 18 Jnr. I realize that speaker efficiency contributes alot. SO, I took the Z speakers and moved them to the other amps. It wasn't even close. The Z is almost deafeningly loud. Even with gain on about 1pm, and master around 11am. DR was at 7 or 8 and while loud, it was tolerable. The marshall (even with Z speakers) is tolerable. Could the fact that some parts are vintage cause the volume to be different? Can a bad PT cause volume to be lower (i.e., not enough juice to keep the power coming)? What about old filter caps? Would they cause too much juice to leak away from the circuit? I can understand a little difference, and the DR and Marshall are sort of close. But the Z is unfrekinbelievably loud. Makes me think somethings wrong with the vintage amps.