Comment by PaulHoule

I'd go get a pro rackmount compressor on Ebay first

https://www.ebay.com/sch/i.html?_nkw=audio+compressor

I had fond memories of using one at the KTEK college radio station where I was (first) the public relations officer and (later) the engineer. I was told we got it so that amateur DJs wouldn't saturate the transmitter. When I told my high school physics teacher (a classical music audiophile) about it I got a sharp talking to about how it hurts audio quality. Today I know it was an early shot in "the loudness wars".

(If you're listening in a car or other noisy environment, dynamic range is a bug and not a feature, however.)

6-channels would be enough for the typical 5.1 system but the "stereo" label on that expensive box makes it seem like it wouldn't do the right thing for home theater, where I think you'd want to reduce the gain in all 6 of the channel by the same amount.