I left the headphones to burn in more today, so they should get a good 10 hours more use by tonight. It is definitely not a bad headphone. I will try it one more time tonight before I return it tomorrow to see if I will possibly change my mind, but I doubt it. It has a great soundstage for a closed back. Instruments are nicely separated, and everything is presented with a lush character. However, I am a big fan of neutrality. This headphone just does not suit my sound preference. It is just too warm sounding for me, and is missing detail in the upper frequencies. Now, my EQ set I created does helps some, but I don't think I will ever be completely happy with this headphone.
Fair enough, it definitely has a bump in the low end, which is noticeable particularly when you're coming from a more neutral headphone, and the high are rolled off -- this is in stark contrast, strangely enough, to the closed-back model just "below" the 1540, the SRH940, which definitely have a good amount going on up top.