I've stayed out of this debate because the sum total of my experience with car amps is a few friends who have installed amps and aftermarket speakers in their cars. Clearly things have gotten a bit heated here, though, so I'd like to try to offer a few comments.

First, it is technically feasible to power a car amp from 120V AC power. Tekdredger sounds like he has some good insight into the mechanics of this, and you might also get a few leads from the way a custom car audio place does their in-store demos. Doing so will likely pose some challenges, but depending on the goal of the project that may be part of the appeal.

Second, there are likely some inherent differences between the home theater and car audio markets, if for no other reason than the differing power sources and space considerations involved in the two markets. I think those differences need to be focused on before we decide if this project holds promise or not - the "explicit proof" that curegeorg alludes to as not being available. It does appear to be true from glancing at a few online sources (including Parts Express, since that site's already come up here) that the cost per watt range for car audio starts lower than for home theater. For car amps rated at 50W to 125W per channel (4 ohm loads typically), prices seem to start around $0.70 to $0.80 per watt, although you could certainly move up to amps costing $1.50 or $2.00 per watt if you chose to. Any of these costs will then need to be increased to account for the expense of converting from 120V AC to 12V DC to power them in a home setting, of course. This could be compared to Outlaw amps (since we're here) - using 8ohm ratings, the M200 sells for $1.50 per watt while the 7100, 755, and 770 all go for $1.29 to $1.30 per watt. If we keep things "apples to apples", however, and look at the 4ohm ratings for those amps the cost per watt drops to $1.00 for the M200, $0.87 for the 755, $0.86 for the 770, and only $0.78 for the 7100. However you look at it, these prices paint part of a picture. The other part (which I don't know about) lies inside the amps themselves - they all do the same basic thing, amplifying a signal, but are there differences in how it is done? What is the signal-to-noise ratio in a good car amp, as compared to a home theater amp? What sort of THD do you see? What impact does the added power supply issue generate? These are the questions that have not been answered here yet. I don't have the answers, unfortunately. I do understand theendofday's reluctance to discard his plan without getting those answers, and I can see how simply saying "don't do it" without at least some explanation is insufficient for him. Even though I have no plans to try this, I'd like to hear some more concrete explanation myself.

Third, we may need to also address the quality of the amps (as pertains to their intended environment) in this debate. If we are talking about a cheap "bargain" car amp that might be considered the automotive equivalent of an entry-level receiver's amp section, then going through the process of building a power supply is likely at intellectual exercise at best - the results should be no better than simply using one of those entry-level receivers. If we are talking about a good car amp, then the cost and effort involved in building a clean and quiet power supply may be the only barrier - but the audio results may be no better and the overall cost even higher than going with a good, economical home theater amp (either an Outlaw amp or even something used off Audiogon).

I guess at the end of the day, I would prefer to get a good amp purpose-built for the home theater environment rather than taking a car amp (hopefully also a good amp for its market) and trying to transplant it into a home system. On the other hand, I have this weird vision of a mysterious power supply tucked away out of sight and a field of surface-mounted car amps mounted across the front wall of a home theater...