Pros: Wonderful mids, comfortable, realistic sound, pretty good detail
Cons: rolled off bass, small soundstage, can be sibilant sometimes
When I compare these to the newer Studio K240s, these win by a long shot. Not only in neutrality and detail, but in build design too.
The Studios have a big mid bass hump that makes everything sound boomy. But the Monitor version has a very balanced frequency response that sounds almost perfect. To me, the treble is very good, but I dislike the spike most AKGs have in the 8-9 kHz range, these included. Although not as apparent with classical music (which these are great for btw), rock and pop and singing definitely is sibilant after a while. That being said, the treble adds to the detail retrieval, which may be why these are meant for studio monitoring use. I also LOVE the mids on these, and they are the phones strong point. Mids are better than the HD 600s IMO. That being said, the soundstage is kind of small compared to many headphones, but still ok.
I also have noticed the bass could be a little more, as it rolls off quite a bit in the sub bass.
I have tested these with both the ODAC+O2 combo and my vintage Nakamichi TA-2A + CDP-2A. Sounds amazing with both of course, but I prefer the Nakamichi as it powers it better and gives a little extra bass boost and it also smooths out the treble a bit. It's also meant to be driven from those kind of sources. With the ODAC+O2, its a little sibilant and bass could be a little more, but this is because of the neutrality the O2 brings. This headphone would do quite well with warm dacs and amps.