Hey thanks for the reply!
Ya I definitely want to put KT66s in the amp, but at the minute I have no money to do it

As long as these work for the time being I am happy. I was just afraid that it may have had a bad effect on the amp, thank you very much for reassuring me!
So more bottom end with the 6L6s, what kind of tone would I be getting from the KT66s? At the minute I can actually get a great tone, like early Zeppelin, so I'd be excited to see how much of an improvement the KT66s would be.