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!
128x128j-wall
Get a pair of Quad 57's - the champions of detail and low-level listening! And you'll only need 20 - 30 watts!
"help with the echo in my room". 

"an open plan house"

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I know a couple of things for sure.
Room treatment as much as you can stand, and or afford.
Call in someone that can help you.. There are some good companies that will help you without, turning the house into some goofy looking place and the partner won't give you "those looks" for it..

It can look nice and not have the studio look..

Echo usually means pretty Spartan.. No walls on the interior, add one or two panels that are mobil.. Fold out walls... All kinds of solutions..

Tubes (valves) NO...

Have fun..
Have you considered setting your system up for near field listening, at least till you can address your rooms weaknesses? Enjoy the music
Best way to enjoy lower level that I know of is via Electrostatics.
I listen to 75db max.
According  to arthur salvator... NOISE FLOOR  is  how low on the  volume dial can you go with all the music being present..The lower you can turn the volume down with all the  music being there  the  better it is.