Perhaps the imedance characteristics are also challenging, but Magnepans are planar speakers, not electrostatics.
Mrsilver123
For a bargain basement solution, I had success driving Apogee ribbons and Martin Logan electrostatics using an Aragon 4004 MK II.
Curious you are not happy with your Bryston as I believe the Magneplanar factory uses Brystons, although perhaps the higher powered monoblocks.
Many also suggest there is nothing like Magnepans with tubes, but high powered tube amps can obviously be very expensive, both to buy and to run and maintain. Audio Research has several to choose from.
Biamping is also highly recommended, where I understand the factory also uses Bryston crossovers.
Perhaps the ultimate would be huge amounts of solid state power on the bass, and tubes for the mids and treble.
For a less expensive solution with my Tympanis, I have been using a Mark Levinon 23.5 with great success for a few years.
This was also recommended (albeit off the record) by someone I knew at the factory.
Good luck.