You might consider a Classe CAP - 151 Integrated Amp. 150 wpc into 8 ohms and 225 wpc into 4 ohms. Used you can find one for around $1,500. The amp and pre-amp can be separated allowing you to add a more powerful power amp in the future and use just the pre-amp portion of the CAP - 151. This flexibility will allow one to follow an upgrade path without jumping into separate amp and pre-amp all at once. I use Classe separates (CA 201 & CP 47.5) with my MG 1.6 QR and am quite pleased with the results. As has been stated on Audiogon many times in the past, Maggies need lots of power and maybe more importantly lots of current to get the most out of them. I suspect the Classe CAP - 151 offers a lot more of both than your Yamaha can deliver.
Good luck.
Good luck.