Originally Posted by Floydster
I just looked on Parts Express, and I couldn't find a kit that would handle more than 140 watts.
Thermal power handling is an almost meaningless specification to look at (it may imply where thermal compression becomes an issue, and you may actually care where you've put a bass driver in a small box and applied equalization to get extension).
For reference level home theater you'll be averaging way less than one Watt (13' from a 86dB/1W/1 meter speaker in a typical indoor environment (where Toole summarizes draw down levels of 3dB/distance doubling) you'll be looking at 1/4W to get dialog at 74dB SPL). Loud but non-night club listening levels still aren't going to pose thermal issues (99dBC on rock music would get you to 40W a side average with such speakers).
If you do need more headroom (nice jazz recordings have over 20dB between average and peak levels, so 93dB total and 90dB/side average playback levels are going to take 110dB listening position peaks from each speaker that may be 116dB at the speaker) you'll do a lot better getting there with more efficient speakers. Disregarding the power limits and thermal compression, in that situation an 86dB/1W/1 meter speakers would require a 500W amplifier (1000W peak but consumer amplifiers are rated with a 3dB crest factor) while the 96dB/1W/1 meter speakers are fine with 50W a side.
This also ignores that you'll run out of excursion before power handling in a lot of situations. Being able to handle 300W in a driver doesn't matter much (it suggests you won't get noticeable power compression if you run it at 15W) when 30W runs it out to its mechanical limits at low frequencies.
I need 230 watts or so, and an 8 ohm impedance (no lower than 6). If the cabinet isn't too complicated, I can build that. An assembled crossover would be nice, but not necessary - the parts would be fine.
You need to decide on budget, placement limitations (ex, the speakers need to be in corners, can be a healthy 5' from the front wall and 3' from side walls, can or can't be in walls with 2x4 or 26 studs, etc.), required bandwidth (full-range, you're willing to cross to powered sub-woofers at 120Hz, etc.), and peak output levels (coming from average listening levels and what the peak to average SPL ratio is in recordings of interest).
Unless you plan on using your speakers at DJ gigs or out doors you're not going to have problems with thermal power handling as long as you turn the volume down after it starts distorting.