Hello, I currently have the Infinity TSS-750 speaker package and am considering trading the sub that came with the system up for a M&K 1250THX sub. I am under the impression that a different brand sub will not create any timbre matching problems with my current surround sound speakers. Is this correct? My current sub only goes down to 34 Hz and I want one that goes down to 20 Hz. I have to admit I am drawn to the M&K 1250 because of its THX select certification and am trying to match that of my Yamaha THX select reciever. Are there other subs around $1k that would be better? Is THX select certification worth the hype?