...a $300 sub that goes down to 20Hz and integrates perfectly with M80s. Sigh.

Carry on...

Sounds familiar, but I'm no help. I ended up getting an EP350v3.

For some reason I started getting a Crutchfield parts catalogue even though I have never bought product from them. I don't believe you could even build a decent DIY sub for $300, much less one within your specs.

But I understand, that wouldn't stop anyone from wanting one.

Did anybody here ever watch the 'Carry On' movies?

You could look at the STF-2 from Hsu, that might work out.

Apparently not. OK folks. The post is FUNNY!! I laughed

Mood updated. sigh...

Reminds me of a scene from "Grumpier Old Men"

Wish in one hand and crap in the other, and see which one gets filled first!

Several years ago I built a sub. I got a 250W plate amp from Parts Express for about $150, and a 15" Adire Tempest driver (awesome sub with huge excursion) for just under $175. The enclosure material was probably about $75, plus misc. costs for filler, hardware and finishing supplies for around $35. That's a bit over your price range for a sub that does a decent job down to about 25Hz. Not sure how well it would integrate with the M80s, but it sounds good with both my M22s and M60s.

For $159, you could audition a Scamp-10 from TCA. It doesn't hit 20hz but comes pretty close.

Seems like it's worth trying for the fun of it.

I want a $300 digital amp no taller than 2U with more than 200wpc.

Ain't gonna happen either.