Building a Music Room

I want to build a dedicated room in my garage for Music. Dont want to get too crazy just a basic place where I can listen without driving everyone in the house crazy.
System is 2 channel only Krell KPS 25sc-Krell 350mcx Monoblocks-Martin Logan new Summits

Any advice or cost from those who have done this etc welcome
Last Summer, I built a dedicated listening room in my basement. We subdivided a very large rec room. Given spousal restraints, the room's final interior dimensions are only about 13x15, but it is totally built for audio. Since we had to put up two new walls to form the space, I had the contractor use 2x6 lumber rather than the more standard 2x4. This makes the walls thicker and a bit more rigid. Also, I have the walls well insulated with heavy fiberglass insulation. This was primarily for sound-proofing, but it seems to dampen some of the resonance nicely in the room.I probably should have used commercial grade sheetrock. It's thicker and has a higher fire rating. My contractor/friend squawked about it plus the costs were going above budget at that point anyway. Are you going to lay a wood floor in your garage space? I just have thick carpet over the concrete basement floor which seems to work well, but wood could offer some benefits. Other features of the room include a new, dedicated 20 amp power line and hospital grade outlets. I also use Realtraps very liberally in the room. I have floor to ceiling Mondotraps in the corners and several more Minitraps along each wall. I have Sonex 2x2 squares all over the ceiling as well. Having a room I can freely play with, with no WAF to worry about on its interior is a great, continuously variable way to tweak things!
In my basement room I decided to lay commercial floor tile (like you see on a Walmart floor) and use large area rugs to help dampen the environment. I'm very pleased with the results.
For a garage floor I'd epoxy paint the floor and use large area rugs as well. Regardless of what is chosen as a floor covering; seal the floor!

Dedicated lines are a worthwhile investment.

Are the garage walls already sheetrocked?
Will the garage door still be a functioning item or will this become a (semi) permanent wall?
How big is the garage?
Ceiling height?
Attached to the house?

If you can get your hands on the recent Acoustic Sounds catalog ( they have a nice write-up regarding the listening room they recently had built.
Why this article is not available on their web-site baffles me. Well at least I could not find it so as to provide a link.
I spent around $20,000 but around half of that was because I built a new garage in front of the old one...So, around $10,000 for me: 25'x 23'x 9' was what I wound up with for my dedicated room. You can see mine by clicking on my system link. Of course I did the labor...labor is around 50% of cost if you hire someone.

How large will your room be? high is the garage ceiling?

I actually built my room under the garage - dug underneath it - in an architect approved design. Good news, your floor will be solid and gently sloped (not parallel to your ceiling). If you can vary the surfacing of the remaining walls and maintain a good width to length ratio, you will likely get very good results from the get-go. Good luck with the project.
If it's DIY our resource section may help you.