I'm just not a believer that a car is the proper listening environment for audio anyway. I've got an "acceptable" sound system in my car... I put in a basic Pioneer head unit with an iPod interface and an XM tuner on it, and I upgraded my stock speakers, but that's pretty much it. I leave the amps and subs to others.
My home system on the other hand...
Upstairs I have a vacuum tube power amplifier that I designed and built last year driving (2) Boston floor speakers. My sources are a Technics turntable, a Yamaha CD changer and of course my DVD player and the TV so I can run HDTV sound through that system. The TV is a 50" LCD rear projection (which needs a new lamp
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Downstairs I have a Mitsubishi 65" RP HDTV as my display, and a DTS surround system consisting of (2) Klipsch KLF-20 front speakers, a Klipsch KLF-C7 center, and (4) Klipsch Legend (can't remember exact model) surrounds, driven by (4) Carver CT-25 power amplifiers, plus a pair of Klipsch KSW-12 subs (and none of my Klispsch is the crap Klipsch that they whored out to Best Buy), all going into an Adcom GTP-750 preamp/processor. My sources are a Denon DCD-3300 audiophile CD Player, a Denon DVD player (again, can't remember exact model), Toshiba S-VHS VCR, and a Dish 900 HDTV receiver. This system rocks. Nothing beats Dark Side of the Moon on LP played on this system.