Onkyo HT-S590

[Avond]

Hello All,

I hope this is in the right place. I don't know much about audio, but I would like to make some incremental improvements when budget allows. I currently have the Onkyo HT-S590 HTIB. I bought it quite a while back before I knew anything about audio and there was no blu-ray yet (at least to my knowledge). I am fairly happy with the surround and center speaker (or could make do), but I would like to improve the bass if possible. I currently have the Sony BDP-S350 blu-ray player. I know it doesn't decode all the lossless audio codecs like the 550 does, but I think my receiver has one set of analog inputs, but I"m not really certain. I guess my main question would be if there is any way to replace the sub I have in this HTIB with a different sub (maybe an active one? I'm not really sure how this works)? My guess is there isn't a way to, but if there is, I'd like to know! I'd like to not replace the receiver just yet. Thanks!!!