you'll play higher frequencies a bit better. Normally people only tune that low if they listen to re-bassed music that goes really really deep. Most of everything from rap to rock will be 35hz to 60hz. rarely do you have any musical information down low unless you go into the rebassed culture where artists like decaf, dj slow n throw, got160s basically create whole new basslines on random music for windy low frequency demos.
so if you just want to play normal music, i'd say 32-36 hz tuning depending on your preferences. 32 wil be for rap based. 36 will be for everything else.