Here's the dilema:

ported box, no subsonic filter on my amp. I could get a sealed box but they're type R subs and I've read they sound bad sealed? I know, I should have bought some good quality subs in a sealed box.....

I found this unit which seems to have a subsonic filter. Anybody used one before? Will it protect the subs from subsonic damage? Any pros/cons you can think of? It's $80 for it.

http://mobileaudiocontrol.com/produc...51&l1=5251&l2=

I have: Rainbow SLC components front, Coax's rear - Audison lrx4.300
2 12" typeR subs - zapco studio 500
Pioneer deh-p9400mp
Any answers/feedback is appreciated!