TubeMagic A1 is a tube headamp
TubeMagic D1 is a DAC+headamp
I would say that the TubeMagic D1 is great for driving D2000! It is very versatile and easy to change the opamps inside to 'attune' the sound towards your preference!
Different headphone have different synergy with different headamp. It is easy to change the opamps inside to improve the synergy with different headphones rather than changing the entire amplifier althogether.
I have not done a 1v1 comparison against the E7+E9 combo before but my bet is that you will be satisfied with TubeMagic!