What's the difference between the HD6 and the A5+?

The HD6 include some pretty significant upgrades over the A5+s.  Among these are:

• Larger redesigned woofer with die-cast aluminum frame for extended bass response with fast dynamics
• New larger custom 1” tweeter for an open and realistic high end and an extraordinary soundstage
• Thicker, low-resonance cabinet
• Upgraded crossover components

In addition to the performance related upgrades, the HD6s also feature:

• Bluetooth aptX and digital optical inputs
• Real wood-veneer cabinet finish options
• Removable magnetic grills
• Solid aluminum remote control