Hello there, in the past few weeks I've been trying to buy an amp,in fact I've bought a yamaha ax-497 , then a marantz pm4001.Haven't been happy with either. Yamaha overwhelmes midrange,marantz it's the bass and lack of midrange.Any ideas of wich of the next would be most neutral sounding? Pioneer a-209r or denon pma-500 ae? thx for help.