The 50's have always been said to be more laid back with less detail than the 60's, 80's, or even the 22's. Probably closer to the m3's. I don't think a new AVR or seperates will help the sound, just provide more power possibly.

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