"Planars/Statics/Ribbons" asylum over at 'audioasylum dot com' is all the Magnepan stuff you could EVER want. The answers and more are in the seaarch over there.
'I am more bothered by inappropriate sounds, hums, etc'
What makes you think the 'cure' is a crossover?
If that is the case, you've got more problems than a new crossover can fix. System ground OK? No loose window frames? Any wacky neighbors?
Elizabeth is 110% correct. Over at the Asylum, you'll find AT LEAST one recommendation per 'inmate'. Which leaves you exactly where you are now. A bunch of recommendations and ideas, none of which you can audition prior to plunking down the cashola. Based on everything I've READ, the Bryston would be the only one I'd buy sight-unheard.
Maggie Mods is an incredible rabbit hole from which some never escape!
I'm using Pure Vinyl to do the crossover digitally with a Mac and a multi channel pro audio interface for multiple outputs.
It's a bit of a different approach but the results I'm getting are phenomenal. A few years ago I would have agreed that digital processing was a choke point but with today's processing power and evolutions in software it is a revelation.