Here's our home's (updated) music library room. It's about 18 by 24 feet in length with built in bookshelves on each wall.

We designed the room so that it would serve our audio purposes as well as be a place where you would want to go and hang out rather than an audio only man cave. We painted the walls with a lighter tan color from Benjamin Moore and stained the trim & baseboard with a dark Walnut Minwax gel stain. We just had the plantation shutters installed which has really helped break up some of the front reflections from our windows, not to mention blocking an annoying street light in front of our home. Drapes in front are linen drapes from Restoration Hardware.  Finally, I constructed a bunch of OC 703 2" thick acoustic panels and covered them with a burgundy fabric from Joanne's and placed them in the front corners and 4 off the tray ceiling. It made worlds of difference, the room was very echo prone, but now its a great blend and not too dead. The panels along with the thick wool carpet tamed the room just fine.

The electrician ran 2 dedicated lines during the build, one to the McIntosh MC 402 and subwoofers and one to the equipment rack. No noise, hum, or ground loop problems thank God.  Amplification is provided by a McIntosh C2300 tube preamp and MC 402 power amplifier which provides more than enough juice for the Avalons.  The REL 212 SEs now sitting on a pair of Auralex platforms replaced a pair of B2 Britannias.  The RELs sounded excellent in our old room as well as in this one.  I replaced a VPI Classic 2 with a Classic Signature bundle (with the SDS speed controller) and a Stillpoints record clamp...amazing how much difference the Stillpoints clamp made.  The Audio Research Ref 2 phono SE has taken the place of a Manley Chinook which was a fine component in its own right but cannot compete with the ARC piece.  Interconnects throughout are Wireworld Gold while speaker cabling is by way of a pair of Wireworld Silver.  Power cabling is Shunyata Alphas all connected to a Shunyata Denali power center.

Thanks to all the members on here for advice during the build and to my lovely wife who loves the room, but has told me that if she has to help me build or hang one more acoustic panel, she will serve me papers!