Advice needed

I am running my Magnepan MG-2.5/R speakers using an old Carver M-200t that has recently developed a relatively loud buzz in the right channel. To replace the amp I am considering the following options:

NuPrime STA-9

Two NuPrime STA-6's bridged into 160-watt mono amps

NuForce STA 120 or STA 200

Essence DPA-440

MicroMega PW-400

Due to space limitation I can't accommodate any component deeper than ten or at most eleven inches. As I do not have easy access to any reasonably good audio equipment dealers I will not be able to audition anything. I would greatly appreciate any advice.