For anyone interested, here are my subjective thoughts on the 5909. I have a Sony Wh-1000xm2 and Wh-1000xm4 available for comparison.
----------
Cliff’s Notes…
Would love to love them... But I don't. Bluetooth calling is broken (will be returning my copy), ANC is mediocre at best, sound quality is nice but not perfect to these ears (brighter overall tonality with slight treble edginess, and bass lacks 'impact'), build quality is superb, the finish is beautiful, comfort is good.
----------
Been using them for a few days. Firmware updated to 1.5.0.5.
Bluetooth functionality—
Out of the box it took repeated attempts to connect via Bluetooth before an 'unable to pair' error stopped occurring. I've never experienced that error with any other Bluetooth device I've used in the past.
Once connected and firmware updated it connects just fine for music. Unfortunately the headphone powers off during Bluetooth phone calls after a matter of seconds, every single time; this renders a critical piece of functionality unusable and it will be returned.
ANC performance—
Disappointing... The Sony XM4 has noticeably better ANC than the XM2, and the XM2 offers significantly better attenuation than the 5909. Based on my copy, I'd say ML's ANC tech is three to four generations behind Sony. ANC performance is what I would expect out of a no-name headphone for $150, not a premium brand headphone selling for $1000. If my sample is representative, ML needs to step up their ANC game if they want to be a competitor in the premium space.
Comfort and Build-
Comfort is acceptable for me. I appreciate the extra ear cup space, as the Sony pinches my ear against the arms of my glasses... On long flights this equals "ouch!". Build quality appears beyond reproach and they're beautifully finished.
Sound Quality-
Sound is superior to the mid-bass dominate 'muddiness' of the Sony XM2 and XM4, but trends toward a bright(ish) overall tonality to my ears, and IMHO needs further refining. At a minimum a treble control is needed to take the slight edginess off the treble. A gentle slope was all I needed to bring the edginess and tonality into line with my preference and smooth out the experience.
Bass is the opposite… a little too soft and smooth for my preference; where’s the impact and excitement when called for?
Conclusion-
Sound quality definitely didn’t wow me, but it’s nice enough compared to alternatives that if ANC was the only disappointment I’d be tempted to keep them, however, poor ANC with broken Bluetooth functionality is a deal-breaker.
Will be interesting to see what Amir’s testing eventually reveals.