Not likely to be a good match. - Al Sekela

Welcome to the Planar Asylum!

Magnepans are all nominally 4-ohm speakers and not very efficient. They need power amps with lots of current drive capability and very low output impedance. These are not easy things to determine from published specifications, but there are some things we can tell from the general descriptions.

The Western Electric 300B is a legendary tube, as it was used in the early days of sound motion pictures with horn speakers. Lots of people build tribute amps that use it for a power tube, but the power output is modest. It is best used as a driver tube for a more robust power tube, such as the 845 or the GM-70, but even these tubes are not suitable for Magnepan service.

Very large pentode tube amps, that run in push-pull, generate adequate power but may still not have sufficiently low output impedance to fully control the Magnepan panels. These amps suffer from what is called "crossover distortion," and are not as highly regarded by tube afficionados as the single-ended triode (SET) amps, such as those with the 300B output tube. The SET sound is considered 'warm' IMO because it is free of crossover distortion. Some SET amps may also generate a lot of second-harmonic distortion, which sweetens the sound, or have limited treble due to transformer problems, which emphasizes the midrange, but I've heard very good sound from some SET amps, just not on Magnepans.

My favorite amps for my MG-20s are the Gilmore Audio Raptor monoblock switching amps. These are free of treble and RF noise problems found in many switching amps, and have about the lowest practical output impedance possible. The midrange is incredibly life-like, and they are able to reveal the smallest microdynamics that give recordings a sense of palpability.

I live in the Bay Area, but will be busy for the next month. If you are still looking at amps near the end of January, keep posting here and I'll get in touch.