Speakers sound too bright.

@rwalsh07, I haven’t read any of the comments so disregard my reply if it is deemed irrelevant.

Have you done an RTA from your seated position?

That should give you the best snapshot of how the speaker is coupling with the room. Doing this is better than any cable change (unless you worried them wrong) or any preamp/DAC/Amp change.

Get a UMIK-1 from MiniDSP. Get this measurement tool for the RTA - https://www.roomeqwizard.com/ and use this method of RTA - this link (https://www.audiosciencereview.com/forum/index.php?threads/the-moving-microphone-method-mmm-for-dummies-using-rew.51333/) and this (https://www.diyaudio.com/community/threads/moving-mic-measurement.262246/) and this (https://www.loudspeakers.audio/en/faqs/mmm-moving-mic-measurement/)

To get to know how the speakers are interacting with the room. That should clearly show you offending sections of the in room frequency response, RT60 and the whole lot of important data.

It is a learning curve with REW but getting this done opens you eyes to a whole lot of ways to deal with issues of speaker/room coupling and how the placement of these speakers in the room can drastically change the tonal identity of a speaker.

Yap aside, most Martin Logans I’ve heard have had an overzealous bite to their lower treble and mid treble presentation... Leading to initial wow factor but long lasting irritation

return them... that is their nature. Martin Logan speakers are bright and if you don't have enough room furnishing to absorb something, they'd be bright in your room... Don't overthink it with the burn in. the burn in doesn't change the Martin logan from bright to not bright. neither will changing cables, amp  or whatever. your speakers are bright and you don't like it, the end @rwalsh07 

@rwalsh07 get two of this - Revel F36 Floorstander