What is wrong with the HK? HK rates their AVR's very conservatively and are a high current design. The Axiom speakers are very efficient and easy to drive. I would think that HK would give you all the volume you would need?

You could by some Outlaw monoblocks to drive just the 60's and let the HK continue to drive the rest of the speakers..

Randy

M80s VP180 4xM22ow 4xM3ic EP600 2xEP350
AnthemAVM60 Outlaw7700 EmoA500 Epson5040UB FluanceRT85