Any thoughts?

Well, yes.

My first competition stereo car had a total of 150 watts output: a 100 watt amplifier driving a pair of 4"/1" coaxials in the dash plus a 5.25" center channel; a pair of 6.5" speakers in the doors; and another pair of 6.5" speakers in the roof (station wagon); and then a second, 50 watt amplifier drove a single 10" dual-voice-coil subwoofer.

The car sounded really good, and either won or at least placed in the top three in every competition I entered it in. The car was not loud. It would only hit 112--115 dB in the SPL portion of the competitions, and indeed this was why I placed second or third in a few events, I got beaten by systems that gained enough SPL points to overcome my sound quality advantage.

That said, 112 dB is still louder than you would ever want to play your stereo, unless the object is to annoy/impress onlookers.

A 4x40 (or 4x60) plus a 100 watt sub channel is plenty of power if what you want to do is sound good, not ridiculously loud.

Still, if you are unreasonably serious about sound quality, then more power is better. You'll get a cleaner signal with less distortion at normal listening levels, and at very quiet levels the sound won't go all "thin" on you. And you'll be able to annoy/impress onlookers as well.

tanstaafl.