So I've been thinking about this, mostly for giggles. I once had a Carmen Ghia that I made 6V6 converters for. It sounded like crap. It's possible I did something wrong, but been afraid to try since. So here's my question: What things might need to be changed to convert an amp? I'm not talking big things like transformers etc as those should work out in many cases, but talking about more subtle things, resistor values etc. Any thoughts on what might need to be tweeked to do this ? Say you are going to convert a BF Princeton to EL84's.... it seems in theory it should be easy ... but... Do the tube adaptors you can buy do other things than just make the correct pin outs?