+1
I must agree. Upgrading your speakers would be the way to go. You can get lots more out of the rest of your system. If you can swing over $5K you can get into a new class of speakers. If you really like the Mac sound, B&W is a common choice to pair with. Other great brands: Sonus Faber (natural / musical) and DynAudio (detailed and dynamic) are also great choices. Since the Mac stuff tends to lack detail, B&W and DynAudio may be really compatible.
+1 Getting Better Sound