Different Tubes for low listening levels?

Is there any consensus that different Tubes shine more light on musicality at lower listening levels (say 75-78db)? I've upgraded from el34's to KT120's and noticed a deal of improvement in deeper tones and power. It's been some months, so I'm considering switching back to see if the same lower levels improve or change the experience. Does anyone have any insight to this? I've also considered room treatment to help with the echo in my room, which I'd assume will help with more detail in lower listening levels. But any thought on tubes? Throw your tomatoes and advice, thanks!