I bought an SW100 subwoofer to use with my PSR S975 about a week ago, so early days yet,but I am impressed. The bass is of course enhanced but there is in my view a subtle but worthwhile enhancement of the overall sound, clear and well rounded. The only slight downside comes if like me you use headphones a lot. When you insert your phones the internal speakers switch off but the sub being fed from the line output keeps on woofing. Easy enough to switch the sub off but if you want a correctly balanced sound in the phones you have to go into the equaliser and switch off the sub setting.When you want to go back to speakers you have to switch back to the sub setting. A bit fiddly but overall I still feel it is well worth the trouble. I only have this for home use so I cannot comment on gigging use but I hope My comments help. Regards Stuart