as i wrote before i always appreciate dweavers opinions on headphones, as it seemed that we had similar preferences in the past. i ordered a k845 (bt version of the k545 with identical sound, when using cable). and was not impressed enough, so i sent it back. ordered a kef m500 instead which i fell in love from the first minute i got it, because of spacious, detailed and natural sound. but i changed some pms with dweaver that made me order a second pair of k845 and now i am comparing them with the kef for the last three days. the akg is not bad at all, but to my ears it is a very mainstream sounding headphone with a decent v shaped signature. headphones like cal!, hm3, momentum etc. have a somewhat similar sounding signature. even though the akg has pretty decent soundstage both in width and in depth they still sound closed. some instruments seem to get stuck in the cups. the kef sounds much more like an open headphone. to my ears it shows more details has more accurate imaging and sounds more live like. it is slightly brighter than the akg but still with a hint of warmth. bass is faster and only slightly less but more so it does not cover the lower mids, as the akg tends to do sometimes.
besides that i compared both to my beloved es700 and this one seems to stand right in the middle of the akg and the kef speaking of signature only. only downside of the es700 compared to the others is, that imaging is not as accurate but still decent.
speaking of comfort the kef wins on my ears hands down. the cups of the akg need adjustment on my head avery 5 minutes. i have a pretty large head though.
just my 2 cent, but it would be nice to hear other comparisons of the mentioned headphones, because maybe i am completely wrong...