unhappy w/ cinema 330s - upgrade to studio 20s?

[benny z]

when i purchased my 330s the major requirement was that the speakers be wall-mountable to surround the tv on our fireplace. since placing the tv in front of the fireplace on the hearth temporarily, we've gotten very accustomed to it and have decided to leave it there as we never use the fireplace anyway. i have a thumb drive with a video of a fireplace to put on for effect. i digress...

anyway, the point is that i've got some buyer's remorse with the 330s. my major complaint is the lack of midbass and a resonance in the lower midrange which is becoming more intolerable the more i listen to them. my listening is a 60/40 split of ht/music. i'm happy with the majority of the midrange and high end, though at times these are a bit bright.

i'm thinking the bookshelf studio 20s might be a better option. can anyone comment as to their midbass performance? i have an adequate subwoofer, but feel i am really missing out on the 90-120hz snap. if i were to go this route i would likely just buy the pair for now and then pick up the bigger center channel as cash permits with the hopes of eventually moving up to dedicated amps and studio 100s for the front.

my final question, i promise... what is a fair used value for a set of 330s in gloss black ($20 per upgrade) with two of the 18" ls-15 stands? i've got 2 weeks' listening time into them.

thanks for your time!

- ben