A word of caution - I cannot really understand what is being attempted here, but Vandersteen does caution against using XLR-single-ended converters with the M5-HP. There are different types of converters. The ones made by the Digital Amplifier Company are pricey, but there is more to them than I can easily undertand or explain. They ain't cheap, either.
@tomic601 - M7??? I wasn't even aware there was such a thing. Prolly more than I can afford anyway. My M5-HPs are in Hanford being inspected/repaired. Yes, I miss them, but they were behaving badly.