The SM 70 Pro is fully solid-state and lower powered than the SE-160. The SE-160 monoblock amps would be a better choice for using power hungry speakers like the Magnepans in a medium to large size room. Plus you'd have the advantage of being able to tailor the sound to your taste by tube rolling on the SE-160's, which is a hybrid design and uses one tube in the input stage. The SM-70 Pro is the brighter sounding of the two amps if I remember correctly.
But if you're talking about running high efficiency speakers that only need a watt or two to play at a decent level, then a single SM-70 Pro would make more sense, and it's less expensive...
But if you're talking about running high efficiency speakers that only need a watt or two to play at a decent level, then a single SM-70 Pro would make more sense, and it's less expensive...