The intent behind my comment was if the criteria for testing was to listen for neutrality and overall sonic balance without deviant quirks or overt personality traits, and in that case, in a blind listening test, I believe audiophiles would give the thumbs up to the 600 over the 650. The upper bass in the 650 has a podgy hump, and the sonic signature is definitely warm, and it's definitely lacking air in the treble region. I've done many A/Bs with these two, and the 650 makes no sense to me, like I said in a previous post, you couldn't give me one for free.
OTOH the HD600 seems to have a small artificial hump in the treble right where it messes up violins a bit and tends to make most music sound not quite truly live like you are there in the room with it since the hump seems to mask stuff just about it, in a sense.
Anyway I did a lot of listening to both yesterday after I had made all of my recent comments.
I guess the HD650 sound stage really isn't any wider. I think I had gotten that impression because I had been using the HD600 for a lot of TV stuff where the audio is not always all that great and the HD650 only for music but also equally because the HD650 gives that feeling that you are literally in the room with the instruments which the HD600 never seems to quite do so I guess I was interpreting that as a wider sound stage, maybe I should have said there is something more somehow live about the sense of the HD650, maybe it's not actually left right wider but sort of more in some other direction or something.
As for the balance, I think ideal might be sort of like a mix between the two.
The HD600 has something weird in the treble that makes violins sound a bit fake and music in general to not quite have that live feel since the hump sort of veils some of the separation and detail in the rest of the treble in a way. Getting to violins again it can almost make they sound a trace electronic in a way and you don't hear the bow vibrating the string sort of in as natural a way as with the HD650. That peak seems to sort of mask the real treble a little and to my ears and the way I describe things makes the HD600 seem more veiled and less in the true treble and darker in the treble since the low part of that is peaked.
Again and again the HD650 just makes things sound more like you are truly there in the room.
That said, for certain things the HD650 might have a slightly odd hump in one part of the upper bass, mostly it doesn't matter too much, and for a decent number it maybe seems even a touch more realistic, but for a few things it can be a bit droning like with the 24bit, 192Hz(?) remaster for Jurassic Park soundtrack. In other ways the bass can be even cleaner and tighter and deeper than the HD600 which can also occasionally be just a trace unnaturally weak in some bass (although not nearly to the extent of the AKG 701, which also has the natural you are there presence and separate treble of the HD650 but is also thinner than both and too thin to be natural, something is just missing lower down that is not realistic).
The initial overall sonic impression is in many ways almost ideally natural from the HD600 and the HD650 can have a touch of that missing. OTOH the HD650 makes it sound more like you are truly listening to the instruments in the room with you and it doesn't have that fake treble bump that makes things sound less live and a bit off. If they could just chop that little treble bump the HD600 might be almost perfect. But that bump just is not natural and for most stuff it makes enough difference that the HD650 sounds better to me overall and more live. Violins for one, since they are something that makes it very clear, are not well separate enough in their timbre and they sound a bit fake and sort of smoothed and not rough and detailed and raw enough and a bit too boosted in a certain particular way, everything actually does, but it's easier to describe it with them. And it can be the same for female voices too. That fake mid-treble thingy, whatever it is in the HD600 just takes away natural rough detail in the treble and makes things sound less live and more veiled in a certain sense and too sort of tinkly and electronically smoothed or something.
Ideally I'd have the HD600 with a touch more of the tight perfection and reaction of the HD650 and with a good bit closer to the HD650 main treble to give a more sense of being there live and to not make violins and other stuff get that treble issue as well as a bit more of the HD650 bass extension and the bass overall (although without the touch of a hump), just sort of merge them, maybe 1 part HD600 to 2 parts HD650 or something along those lines.
