Room Treaments - Where To Begin...

The best thing you can do, is to very precisely place your speakers by listening and using REW.

Take a look at the Before and after, with absolutely no room treatment. This living-music room is the most difficult room to make music sound good, vaulted ceilings, L shaped lots of little right angle little walls, a fireplace, and a lot of windows and skylights. On top the house is made with wood sticks, plaster walls, the wood floors are suspended, in other words a resonance box.

Here is the before and after, as you can see the bass was way too loud. Look at the dip between 200Hz and ~350Hz. 

Some could argue that I need more energy from 300Hz down, I will try new tubes to lower the brightness  and see what the tubes do