First off I would like to say hello to all this is my first post. I have looking around for about 2 weeks now. It is almost winter now so I am working on my HT so I have something to do for the winter. Here is what I have now Mitsubishi WS-55315 55" Projection TV Yamaha htr-5760 receiver Yamaha NS-6490 bookshelf speakers for surrounds,Center & Back Cerwin Vega VS-120 fronts and a JBL PSW-D112 (Amp dose not work) What I am doing now is I have just bypassed the Amp in the JBL sub because I got it off of e-bay last winter knowing it had a bad amp. The amp that was in there was a 250watt RMS. I am using a old Technics SA-AX540 receiver to power the amp (Bridge front channel) Seems to be working GREAT! For movies but not so good for music. I have put a order in for a QSC RMX850 pro AMP and should have it Monday. Here is the first Question that I have. When I play music with the JBL sub it is just kinda muddy now I am not sure how much power I am putting into it but the receiver I am using it on is rated at 100 watts RMS per channel I am bridging it so I think it should be about 200?? The JBL sub is 8ohm. I did use Avia and did a test on the sub and she work nice all the way down to 20 I must say WOW have never felt that before....lol Now would anybody know if I put that QSC RMX850 on that JBL if that would help it not be so muddy when playing music? I Like to play my music loud at times so bass output is very important to me. That is why I have my Cerwin Vegas up front but with the Yamaha 5760 I can't get the bass output I could before with my old receiver so I need to use a Sub. I have been looking at the Adire DPL12 with the PR15 I would use the sealed box plans for that sub from Acoustic Visions website How would that work for bass output and SLP's? I would use the QSC amp for just the sub too much amp? I am open for any other subs that would work for me the room it would go in is 14' 7" x 12' open into a dinning room that is 13' 4" x 12' 3" both rooms have 8' 6" ceilings. I plan on building my own box as long as I have plans to use. I would like to spend about $200 on just a sub. Would i 15" work better for me maybe a 18" I dunno this is why I need some help....lol P.S. Box size in not a problem. Any input here would be great! Thanks!