Audio Systems: Upgrade sound, klipsch speakers, enclosure solutions

Question
New '09 Enclave with basic sound system and XM needs upgrade! The sound is
so tinny. Hate to go to Best Buy for some dork to fiddle with it. I understand GM
wires nearly everything thru the radio, so would I be better off having dealer
upgrade or what?  Don't want DVD. Trying to get best quality sound for the
buck, naturally.

Answer
Hi Susan,
From the text, I semi-presume you want to install as much of this as possible yourself? At some point you will have to allow and pay someone to do the work (unless you do it). A reputable local professional audio shop would be a better choice than Best Buy (and usually better than the dealer in purely audio matters).
I almost always defer people which want to upgrade existing factory systems to the best resource I know of [for that] so you will be best off starting there:
http://www.crutchfield.com/app/car/mycar.aspx?
This way you can input exactly what you have (navigation system or not  ect). Once that is done, the website will only show items which 'fit' or are compatible. This alone can reduce a lot of confusion as you start going through this upgrade.
Many, decent XM solutions are available for that vehicle but realize that XM alone will not cure the 'tinny' issue.
My advice on an XM headunit is to choose one that has the features you need/want and is the least expensive.
As to speakers, I would suggest some efficient Polk Audio or Klipsch speakers (that way you will not need tons of power to get them loud). That said, speakers and a headunit should fix your 'tinny' sound problems (unless you are a soon-to-be-deafened basshead, in which case you will need money, large speakers, a tuned enclosure, crossovers and power amplifier(s) to run them).

If you want a sub, the crew at Crutchfield can help you with that too (from the planning stages all the way through installation/final setup).
Bazooka makes some very effective, all-in-one, self-powered subwoofer/enclosure solutions.
If you need a live person, use their toll-free number 1-800-319-8264

If for some reason you do not like what CF is offering, you may be best off using a local professional shop for (at least) the labor end of this idea. Just be sure you audition some of their finished vehicles (first) so you know they are capable before you invest the doe!
*Oftentimes these shops will install what Crutchfield sells so keep that in mind as your shop. Keep your options open and decide once you get more pertinent, specific data.

Good luck. I am sure you will be in good hands at CF but do not hesitate to let me know if you need any further assistance.

Sincerely,
Jerry Mael
http://www.allexperts.com/ep/835-62518/Audio-Systems/Jerry-Mael.htm