That was my original thought but many say $300.00 can't buy a musical sub.
Yes, but the bass on a $300 "non-musical" sub will still sound better than $300 in electronics to boost a speaker that can't handle bass at all. If you insist on electronics then most any AVR with EQ can do what you want.
My speakers go down to 50hz and sound great with most movies.
However there's the odd movie where the soundtrack is weak (FEARLESS VAMPIRE KILLERS) and I would like to boost the bass to make it sound closer to the good sounding discs.
I should say I mainly buy older films where I'm lucky if they're in stereo and live in a apartment where I can't rattle the walls if I wanted too (I don't).
That would be my main concern about getting a sub.
About the MiniDSP ...it was already suggested so I looked it up but I need something I can turn the bass up and down and hopefully bypass most of the time.
Thanks for the suggestion though!
I'll definitely check out the sub recommended along with the HSU STF-1