Hr1, Magnepan speakers are famous for being current-hungry and very hard to drive, not a typical load.
The OP has BW 801 speakers, an easier load.
So, IMHO, your audition does not prove unequivocaly that amplifier A is better than B, it only shows that the Burmester amps were very happy to drive the Magnepan speakers.
Murrayp, I believe that you would be better off by upgrading your speakers, because your amp and digital rig are recent, top tier products.
The 801 is an old design. BW and several other speakers manufacturers have evolved their designs by leaps and bounds, several new speakers are much better-sounding than your 801s. The 801 large/heavy woofer is quite difficult to control, it tends to sound overweight and slightly boomy if not driven by a very powerful amp with iron-fist control of the bass, therefore your success with the switched amp.
I suggest that you audition Sonus Faber, Verity Audio, Vienna Acoustics and Revel speakers. These are only a few examples of speakers that certainly will better match your electronics and improve your system's sound quality.
Good luck