^^^I couple every other set of speakers I have with a sub. I use my 20/20s with an alesis preamp(I think like 120w), but only use them to master recordings. They actually give you a good sense of everything going on when a sound is coming into your studio from outside, but I hate them for anything done completely in my studio.
IMO they're pretty flat and although I agree the mids and highs seem harsh, it's kind of convenient for mixing/mastering. When I put them with my sub, they sound pretty much like any other speakers coupled with a sub. I use a 200w computer gaming speaker sub and blast it, so rather than risking blowing them, I hooked up some Sony Bookshelves that IMO sound better coupled with my sub.