Adding amp to integrated amp

I am using a new Music Hall A70 integrated stereo amp with my new Martin Logan Vistas. They are 4 ohm speakers that can dip down below 2 ohms. The MH integrated does 185 into 4 ohms and sounds pretty good. But I know ML speakers love power and I could get better control with a larger amp'

The Music Hall has preamps outputs'so would adding a nice amp and using the MH for my preamp improve my sound.

Also would my integrated amps volume control still control my main volume. Thanks for any help.