I had the pleasure of listening to the M30s and VK55 and VK75 at a dealer.
I find either amps can drive the M30s well. The VK75 with its larger power has more control compared to the VK55.
Neither will sound bright but i find it at times a bit too warm for my taste.
In the end, i did not pursue the BAT route.
However i have read some guys at the forum mating the VK75 well with the Harbeth SHL5s. that might be a different story all together as the SHL5s are more extended and detailed compared to the flatter M30s.
Hope that helps.
I find either amps can drive the M30s well. The VK75 with its larger power has more control compared to the VK55.
Neither will sound bright but i find it at times a bit too warm for my taste.
In the end, i did not pursue the BAT route.
However i have read some guys at the forum mating the VK75 well with the Harbeth SHL5s. that might be a different story all together as the SHL5s are more extended and detailed compared to the flatter M30s.
Hope that helps.