Thank you exact answer i was looking for and i greatly appreciate it . Now while the audyssey setup did set up the speakers at 50hz , i have to admit they sound pretty good to me , i have heard no distortion and i usually listen at a volume of about 50-60 on the onkyo 616 receiver . i have not heard much bass coming from the sub , i believe i may be hearing a bit more coming from the sony's , i could be wrong . the sub i have is the polk audio psw108 - http://www.polkaudio.com/products/psw108
As asere says, that sub isn't exactly over-endowed with power or the ability to dig deep. Ultimately, let your ears be the judge and go with what sounds best to you. Your next upgrade would be a truly competent sub IMO - maybe something from the SVS range for example. Follow that with a speaker upgrade. It is worth checking out the classified ads to see if there are some good used bargains around - that can save you a lot of $$$.