I've been a proud owner of an SVS 20-39PC subwoofer since purchasing it in Sep. 2001. However, I've been thinking lately of adding a second powered SVS Subwoofer for more bass output. Particularly the 25-31PC+. I'd like to combine the low frequency output of the 20-39PC with the high SPL capabilities of the 25-31PC+. My current setup consists of the Onkyo TX-DS575X Reciever and the Onkyo DV-C501 DVD player, with Infinity Interlude speakers and the 20-39PC sub. I don't want to get rid of the 20-39PC because I absolutely love it. Can you mix a 20-39PC with a 25-31PC+ and get positive results. Does anyone else have an SVS setup with one type of SVS mixed with another and what kind of results do you get?