Here is a quick A/B I did this morning between the Mikros 90 and the K545.
OK, A/Bing the M90 against the K545 this morning after a night of burnin. I have a small volume controllable splitter so I could volume match between the 2 headphone (done by ear so probably not perfectly volume matched but close). In this test I am using my desktop computer paired with my Little Dot DAC1 and a Bravo Ocean amp with stock tube.
Here is one of the tracks I am using for testing. This one has some seriously nice sub bass.
I then used this Patricia Barber - What a Shame song as a second track for overall listening.
The end result was the K545 winning the sub-bass end still but even with only one night of burn-in the M90 was getting close and good enough I could be pretty satisfied. The M90 has more warmth than the K545 though but only slightly, to me it has a very similar midrange to the HP50. The added midrange did bring out the sibilance inherent in Patricia Barber's recording though whereas the K545 was slightly more relaxed and enjoyable in that regard. I think the M90 managed the drum kit a little more cleanly though and does snares and cymbals a bit better. The K545 has a more spacious sound stage though.
I would say the K545 offers a slightly deeper bottom end and a slightly V shaped signature in comparison to the M90 but we are talking only shades difference between. Between the added comfort of the over ear design and less clamping of the K545 combined with a slightly more relaxed sound the K545 is the ultimate CHILL headphone for relaxing and just floating away in your music. The M90 on the other hand with it's stronger clamp and slightly more aggressive and detail oriented sound is an excellent serious listen headphone and better portable option due to it's higher isolation. They make one hell of a one two punch for me.