I have the PSW505 with two pairs of vintage bookshelf speakers-KEF C-40 with dual 8"drivers and B&W 601se-all driven with a very cheap Sony 7.1 receiver, and I too first expected the "thump" like a disco set up or something. Only after letting the setup run as it wanted for a couple weeks did I finally accept that the sound was great-it was my expectations of the windows cracking or at least my butt to feel it - that were in error.
This setup is about 80%-90% music and the rest for gaming. in games, the bass does a journeyman job in reproducing explosions-no windows cracking but I've had to tone it down because I'm sure it's much too loud for the neighbors at 3:00a.m.!
I plan to upgrade the sub-let's face it; it's a bit out of its league with these bookshelf speakers, but for now, it's doing its job just fine. This setup is near-field, in a small room, and it's the replacement sound system for my PC, so of course it's not the typical setup. I know-2 sets of speakers for near-field? But I just can't decide which pair sounds better, and really, it's such a lush sound, I can't bear the thought of removing one set or the other. hehehe. I haven't done it yet, but I do have a couple of fairly nice center channel speakers to use. So far 2.1 has been more than adequate.
i7-2600k @4.4ghz/gtx 780(stock clocks)/Samsung 830 @256gb/WD Veloc. 1TB/Sound via Sony 7.1ch cheapo/B&W 601se/KEF C-40(dual-8"driver mini-towers)/SVS PB-1000 sub/FiiO E17 Alpen DAC/Audio Technica M50 headphones(never used! heheh)/Crossover 2560x1440 monitor