Speakers sound too bright.

Ignore the app. Make sure the amp’s positive (red) terminal is connected to the speaker’s positive terminal and the amp’s negative (black) terminal to the speaker’s negative terminal. On both speakers. If one speaker was connected backwards, the bass is out of phase and will cancel out.

If the speakers are connected correctly (see above) and they are still too bright, try replacing the positive terminal strap that connects the upper and lower positive speaker terminals with a small value resistor and connect your speaker cables to the lower set of terminals. 1 ohm, 1.5 ohm or 2 ohms will drop the level of the midrange and and high frequencies a touch, more with the higher values.  5 or 10 watt resistors are far cheaper than new speakers!  And before I get roasted for modifying the crossover, please note that Wilson, Magnepan and others offer this same option to tune the level of their high frequencies, too. Those M-L speakers are excellent, don’t give up on them!

As someone once said " shiit in shiit out " or something like that. 

Someone else mentioned esl15a as a comparison and I would highly recommend that speaker instead of what you have,  on the other hand it's a bit more expensive 😉 

Run the lumin in dsd mode that sounds warmer 

"Ignore the app. Make sure the amp’s positive (red) terminal is connected to the speaker’s positive terminal and the amp’s negative (black) terminal to the speaker’s negative terminal. On both speakers. If one speaker was connected backwards, the bass is out of phase and will cancel out."

Maybe not. Maybe the app is correct and one of the speakers has reversed magnetism? This does happen and I have a professional JBL woofer like this which is reported by one of their authorized service reps as happening for about 1 in 50 woofers!

I just couldn’t get the two woofers to phase properly when connected the same. I discovered that when a compass is held up to the front of the two woofers, one shows north and the other shows south! YEAH THEY DO!!!

Or maybe the wires are crossed inside the cabinet and the external connection would appear correct?

A 1.5 volt battery is probably the best way to check.

To rule out a speaker being wired incorrectly internally and assuming you have your speakers hooked up correctly, just play tracks 22 and 25 from this — no need to mess with resistors and such. Left should be left, center should be center, and right should be right and if all that lines up your phase is fine. I continue to think it’s break in, but you should consult your dealer to get their thoughts as well.

http://www.youtube.com/playlist?list=OLAK5uy_ndrls3SVVIl_vwa6lSQILyH7DnQGCevqg