[David]

OK my turn to muddy the water. After doing what Mike said to do, look at the wattage rating of the transformers. The more watts the more $$$$  so a 50L6, 50A5, 50B5, an 50C5 in a AA5 set max power output around 2 watts. Full volume on a AA5 set IMHO not something I want to hear. Putting a 10 watt trans in a AA5 set is overkill. In the future when going to yard sales or flea markets look for organ donors mostly 60s set with printed circuit boards. Plastic cases that are beyond repair and a cheap price. Stay safe David