Pass labs XA-160.8 monos - or -  Mark Levinson 536 monos for Magico's

@fsmithjack   I'm a Pass Labs fan but not having heard the MLs I cannot speak to that comparison.

However, if you are open to other amps, @rsf507  's recommendation to pair your M1 SE (M12)  with the M28s, is an excellent one.

I was very impressed with the M28s (by themselves).  Once they were fronted with a full on M12, those I was with for that initial audition gave the intra-brand pairing even higher marks. I believe albertportis is listing both components.

All the best with your search and final choices.

It has been widely rumored that Alon Wolf is very fond of Hegel amps with his speakers, so I'd definitely add them to your list.  Also, if Clayton M100s or M300s are available they're also worth a serious look along with Pass and ML.  I heard the Q7s with some Vitus monoblocs and they were sublime, so that might be yet another option.  I'd enthusiastically add Gryphon but not sure if they have US support here yet.  The first thing I'd do is ask Magico what they'd recommend given your setup and tastes.  Great speakers!  Best of luck in finding the right amp.  Let us know what you end up with and why, as I'm sure it will help lots of Magico owners going forward. 

Going for the Pass Labs XA160.8 Mono-Blocks and now trying to find a good matching preamp. Thinking maybe a neutral sounding tube preamp. What do you guys think?

Nagra Jazz or maybe Zanden 3100?

Any thoughts, idea or recommendations? 

I’m completely satisfied with an AtmaSphere MP-1 into Pass XA-160.8 monoblocks. It’s a super clean direct coupled differential balanced tube sound. Give Ralph a call.

Fior tube preamp i would certainly look at VAC wonderfully made and sounds great with depth,sound stage,dynamic impact and great bass.The company is wonderful as well.