Harshness will depend on the quality of music recordings you have, as well as listening environment. Both m60s/80's would work fine tone wise with the vp100.

I think most of use unbalanced anyway, so no worries.

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