Klipsch are efficient speakers so pretty much anything will drive them. What you heard at your friends is what you'll get using anything else. Klipsch are known to be a bit on the harsh side which some folks like, but you obviously don't.
Unfortunately, in this price range, you aren't going to find too many speakers that dip below 80Hz with any kind of authority. The Ascend Sierra-1's put out a fair amount of bass for bookshelf speakers, but they're substantially higher than $500. I would check out Monitor Audio Silvers which several online dealers carry for a great price. You may also like KEF. I also would give Aperion a try as there's no financial risk in doing so. Another option is to check out tower speakers from EMP and Elemental Design both of which sell pairs at $500.