This is my first post, so excuse the Noob-E-ness (yup just made that up). Anyways I spent about 2 1/2 hrs at Guitar Center today looking for some new cans. I went in with my mind set on buying the SHR-440's but while I was there I saw they had SHR-440, ATH-M45's and KNS-6400 and 8400's. YEY FOR ME!! I brought my iPod 5.5 and went to work. For myself I was looking for something VERY transparent, no coloration at all. I listen to mostly jazz, my degree is in jazz studies and my collection is HUGE and I use all FLAC and Lossless tracks. I listened to all cans with the same track same volume, made sure it was a tune I knew front and back so I picked "Nardis" off of the Bill Evans Trio record Explorations (1961) The 440's seemed to have too much bass and didn't seem to have enough airiness, seemed to be more "IN YOUR FACE" Moved on to the ATH-M45's first I must say these have an amazing build they feel SOLID. I had the same problem, they seemed to have a bump in the bass and mids. I changed it up a little and listened to some John Scofield and they sounded great, bass drum was kicking and snare was "punchy." These IMO would great for electric instrument jazz and rock. Now on to the KNS-6400 and 8400's. The 6400 and 8400 looked somewhat the similar. I loved to cushions on the 8400's but again too much bass for me. Then the 6400's the same was what I was looking for highs are great for the high hats, mids let the piano and archtop guitars ring and sing and lows were not overpowering. The bass on Bill Evans Trio records is extremely important since Bill is going all over the place with his chord voicings but didn't want it to be overpowering. These are super comfy and light weight, even though they stick out a little but hey small price to pay for sound. I love the fact that these cans are flat and with no boost in certain frequencies, I also feel these are very open, great sound stage. Needless to say I went ahead a picked up the 6400's I was there so long trying the phones that they forgot about me being there lol. I would highly recommend these to anyone that is looking for a transparent, flat, and analytical set of phones. I have not taken these off my ears since I bought them, I even ate dinner with them (GF) didn't like that very much... But I will be changing to the 8400's ear cushions...