I have found myself listening to LPs and CDs recently after a long period of ignoring my music collections (most of which were in storage for years). My existing 2-channel set up is quite dated--a mid-90s NAD 713 AV receiver, an NAD CD player of more recent vintage, PSB bookshelf speakers circa 2005 and an 80's Harman Kardon T-45 turntable. The lack of bass has always been the most conspicuous shortcoming of this set-up and since i seem to have rediscovered the joys of listening to music, I want to add a subwoofer. My listening room is an open plan arrangement, the main listening area is about 12 feet square but there is no wall separating it from the next living space, so the room overall (which includes my kitchen) is roughly 12 x 30 feet, with hardwood floors. Music only, both pop and classical, I'm not seeking bone-rattling effects. I have been looking (online only) at the HSU ULS 15 MK2; also considering the (more expensive) SVS SB-3000 and the (less expensive) ELAC Sub3030. It's a bit frustrating not to be able to hear before ordering, but that seems to be what I'll end up doing. So, my first question: does the DSP sound adjustment software make a big difference? That's the attraction of the ELAC, and I gather there is something similar with the SVS, though it isn't clear to me what it does in the case of SVS. My second question: since a single subwoofer will be the only addition to my system in the immediate future, does the age of my other components create limitations that I should consider? The NAD receiver does have a mono sub out jack, though I'm not sure it has a setting to limit the bass to the bookshelf speakers when a subwoofer is attached, if that's important. Thanks in advance for any advice.