Hi Fred, I have used the Rowland M625 stereo amp, and now am using M725 monos on Vienna Die Muzik speakers, which have relatively difficult impedance characteristics. Robert Harley has just reviewed very favorably M725 and believes that they excell on the large Magico QW7 flagships. So I suspect that either M625 or M725 should do well on Sofia 3.
For a preamplifier, I am using the Rowland Criterion, whose audio circuit is essentially the same as Corus.
There is no problem at all for both M625 and M725 to control Muzik, except that M725 do an even better job than M625.
The difference is that M625 appears to generate a stage and images that are about 65% of the size of M725. Furthermore, I found M725 to be even more transparent and tonally rich than M625, probably because M725 uses low capacitance ceramic motherboards. Finally, while M725 seems to have an unlimited power reserve and authority because of a 1500W power supply on each chassis, M625 seems on occasion to be nearing its limit in authority during very difficult passsages, probably because it as a single 1500W supply shared on two channels.
The reason why I am saying all of this is that if you are using only digital as a source, you may not need a preamp at all.... Aries does even better on its own than when driving a preamplifier. With the same investment of M625+Corus you could get a pair of M725 monos, that you can drive directly with your Aeris.
Regards, Guido