I have the 6A3 courtesy of Francis,driving AER MD2's in an active two way Oris horn config using a Trinnov ST2 for room optimisation and its digital 2way crossover feature.
The 15" bass is driven by a MC2 MC450 at the moment but Francis is sending over his other 6A3 so I can have a play with a fully active setup using the 6A3's
Got my BD Design Ref 2010 bass cabs almost finished,some pics on the wam in the DIY forum looking forward to getting it all together