Just to reinforce what has already been said, it really just depends. Obviously pre and power amps by the same manufacture are build with each other in mind. That said I find many manufactures tend to excel in one area more than the other, finding synergy between varying brands can be very rewarding.
I went for a SS power amp with plenty of grunt, well made and at a decent price in the from of a Quad 909 and then paired it with a Croft Acoustics valve pre-amp and am very, very happy with the results.
Have you tried your M-DAC in pre-amp mode? Many users report good results. I’ve heard those arguing for and against a separate pre-amp plus M-DAC so would be interested to hear any findings you may have.