Haven't received it yet :/ Yeah, it's as you would expect - the A63 has tighter bass but also less of it, more forward mids, and smoother treble. The Piston sounds boomy in comparison but has better bass extension also. It's warmer and more full-bodied. A little more veiled, but not as much as you might expect from such a bassy earphone. Except for the bass, where the Piston loses a bit of refinement/control, I didn't think either had an advantage in detail, etc.