Ayre KX-R or Krell 202 with Martin Logans

I do not find the KX-R to be to forward or trebly but i have not heard it with Krell amps. I have not auditioned the Nagra PL-L but I have heard good things. I plan on auditioning in the future.

I really think you need to listen for yourself with your amp and speakers.

This is an off the wall suggestion. I'm not a fan of many tube electronics but I auditioned an Asthetix Janus last week and I was left almost rethinking preamplifiers. My favorite feature was the ability to invert phase via a remote control. One of the most frustrating audio issues I find is an almost complete lack of concern by recording many engineers to have phase continuity. Another very nice feature is cartridge loading via remote. Again, another trick that can improve some LP playback.

"part of a home theater setup"? Are you familiar with the Conrad Johnson MET1?

no not familiar at all with CJ electronics.

If you want the new preamp to be part of your home theater system and integrate with your Meridian, you might want to consider a Conrad Johnson Premier 17LS which has a home theater bypass feature. I have used mine in a combined home theater/2-channel setup and it has been great.