You want something that sounds as good as high quality headphones? Get high quality monitors....

My Mackie HR824's sound incredible, and go so low (flat down to 42Hz and plenty below that) I don't need a sub, which tend to get overused in most 2.1 and 5.1 systems, anyway.

Probably some slightly cheaper that approach it, but there's a distinct reason they cost a lot more than Logitechs....