Also, make sure you have some soft of EQ. AudioBooster won't work since they are not wired headphones. I use PocketPlayer because my play/pause buttons work with it and it has a TF3D plugin that overrides the built in player from taking over when pushing these buttons. CorePlayer also has it's own EQ.
With no EQ adjustment (flat), BT headphones sound horrible. I've got the Sony
DR-BT21G/B and I love them. Battery life is great on both the phone and the headphones. Sound quality is great as well as range.