[audiojun]

One thing I've noticed is the amount of sibilance present in many recordings.  I wasn't all that aware of it until recently, and now I can't un-hear it!  At first I thought it was the cans, but I know the 600 is one of the least sibilant cans out there... so it must be revealing more of it that is present in a recording, if any.  There are some tracks where there is no sibilance, and some where there is a great deal of it, so I doubt it's the cans.

I did a bit of reading up on it and it seems to be a sore sticking point in the music industry, with artists trying to avoid it, though I heard some pronounce it specifically to compensate for muffled AM/FM radios, which is fascinating.  There is a crap ton of sibilant recordings from the 80s.  I even went to talk to my roommate a minute ago and heard sibilance in his voice!  It's just something I didn't realize was happening until my cans got a bit better.

I notice that in many vocal tracks, sometimes when mastering they purposely enhance those tsk ssh sounds at the end of vocal note to give a sense of air, but it doesn't play well with the HD600 though since it's over done and starts to be annoying.

The HD650 down plays it a bit, it makes those sibilant recordings more approachable. I feel the HD600 still reproduces vocals better overall.

 

[madwolfa]

The HD650 down plays it a bit, it makes those sibilant recordings more approachable. I feel the HD600 still reproduces vocals better overall.

 
I gave HD650 a shot and sold it after couple months. It just lacked clarity (compared to HD600) and sounded muffled/boring to me.

 

[MWSVette]

   
I gave HD650 a shot and sold it after couple months. It just lacked clarity (compared to HD600) and sounded muffled/boring to me.

 
Me too.  I have the Sennheiser HD598, 600, 700 and 800.  I did have the HD650's but they just did not have the detail and clarity that I like so I sold them.

 

[audiojun]

I gave HD650 a shot and sold it after couple months. It just lacked clarity (compared to HD600) and sounded muffled/boring to me.

Yeah making bad recordings less sibilant also makes good recording lack air veiled and darker. I hated my 650 treble response so I modded it. The modded 650 is so resolving with clarity it brought out all the fine details and you just forget it's supposed to be a dark headphone.

 

[ColtMrFire]

Yeah making bad recordings less sibilant also makes good recording lack air veiled and darker. 

 
Exactly.  I tried using a parametric EQ in JRiver and lowered 6khz through 8khz frequencies a decibel or two as an experiment.  It took care of the sibilance, but sucked the air out of low level detail.  There is a far off, low level guitar on a wonderful song (Spanish Harlem by Rebecca Pidgeon) that sounds like there was actual AIR around it and gives it a 3D feel.
 
The EQ literally sounded like someone threw up a blanket between me and that distant guitar and the air disappeared, and it was just a flat, 2D, slightly muffled wall of sound coming from that direction.
 
What I've found is that sibilance is either intentionally left on a track or not there because of EQ in the mastering process.  Really sibilance is everywhere, when people talk, so it's natural... just depends on the degree to which it's pronounced.  
 
I highly recommend getting Chesky Records Ultimate Demonstration Disk (which has the Rebecca Pidgeon track), to really show what the HD600 (or any high quality headphon) can do.  Really, it's great demo material for any component... cans, amps, DACs, cables... does a good job of revealing strengths and weaknesses in a system.

 

[jazzy007]

Yeah making bad recordings less sibilant also makes good recording lack air veiled and darker. I hated my 650 treble response so I modded it. The modded 650 is so resolving with clarity it brought out all the fine details and you just forget it's supposed to be a dark headphone.

Are you talking about removal of driver rear damping foams?
 
I removed my HD600 rear foam awhile ago, bad idea, it ring like crazy, there is no control on the sound, due to metal ringing without any damping foam to damp it. There is reason why Sennheiser place a rear damping foam, and it is there to damp the metal ringing. Yes, sound became more revealing without damping foam, but that ringing was just driving me crazy.
 
What I did was place a pair of foam came with a cheap earbud, smaller than original rear damping foam size, in place of original rear damping foam, which was disintegrated from removal, and spread it as much to the side under plastic cage holder as much as I could. This create a thicker damping effect in middle part of driver rear, but it allow 1/4" of metal to to be expose, and I actually like the sound better this way than original or without damping foam. Metal ring is both properly damped and also slightly exposed. This eliminate ringing sound and also create more revealing sound at same time.

 

[Bob A (SD)]

Yet another reason why I will not try mods that are not easily reversible.   jazzy007 I'm glad you were able to recover!

 

[DavidA]

  Yet another reason why I will not try mods that are not easily reversible.   jazzy007 I'm glad you were able to recover!

Same for me when it comes to mods

 

[Midgetguy]

   
I gave HD650 a shot and sold it after couple months. It just lacked clarity (compared to HD600) and sounded muffled/boring to me.

That's what I felt. My bro has one and I bought an HD600 so I compared mine to his. It also felt kinda muffled to me somehow, didn't like it quite as much as the HD600's sound.

 

[audiojun]

Are you talking about removal of driver rear damping foams?

I removed my HD600 rear foam awhile ago, bad idea, it ring like crazy, there is no control on the sound, due to metal ringing without any damping foam to damp it. There is reason why Sennheiser place a rear damping foam, and it is there to damp the metal ringing. Yes, sound became more revealing without damping foam, but that ringing was just driving me crazy.

What I did was place a pair of foam came with a cheap earbud, smaller than original rear damping foam size, in place of original rear damping foam, which was disintegrated from removal, and spread it as much to the side under plastic cage holder as much as I could. This create a thicker damping effect in middle part of driver rear, but it allow 1/4" of metal to to be expose, and I actually like the sound better this way than original or without damping foam. Metal ring is both properly damped and also slightly exposed. This eliminate ringing sound and also create more revealing sound at same time.

Removing the foam in the back does do that but I removed the whole spider cage behind it and it took the ringing away.

 

[DavidA]

  That's what I felt. My bro has one and I bought an HD600 so I compared mine to his. It also felt kinda muffled to me somehow, didn't like it quite as much as the HD600's sound.

This is interesting because I had the HD-650 for a while before getting a HD-600 and to me the HD-600 is a little thin and a touch to bright sounding.  It seemed more amp picky, like the HD-800 which only sounds good on the BH Crack, so-so on the Ember and less so on the Lyr2.  I guess I like the Sennheiser "veal"

 

[Midgetguy]

  This is interesting because I had the HD-650 for a while before getting a HD-600 and to me the HD-600 is a little thin and a touch to bright sounding.  It seemed more amp picky, like the HD-800 which only sounds good on the BH Crack, so-so on the Ember and less so on the Lyr2.  I guess I like the Sennheiser "veal"

But did that feeling have anything to do with the fact that you had been using the HD650 for a while before buying and trying out the HD600? Because I have that same kinda feeling when going between the HD650 and the HD558, which to me sound kinda like the little bro of the HD600, just missing some bass presence and of course slightly lower overall fidelity.

 

[madwolfa]

  This is interesting because I had the HD-650 for a while before getting a HD-600 and to me the HD-600 is a little thin and a touch to bright sounding.  It seemed more amp picky, like the HD-800 which only sounds good on the BH Crack, so-so on the Ember and less so on the Lyr2.  I guess I like the Sennheiser "veal"

 
I think it largely depends on what kind of music you prefer. Nothing to do with amps, in my experience. With properly recorded audiophile grade stuff (acoustic/jazz/classical) HD600 sounds just right, whereas HD650 is more satisfying with lower fidelity stuff like pop/rock/metal due to more bass presence and slightly tamed upper-mids/treble.

 

[Schmidter]

If I can run DT 880 250 ohm. Can I then also run these pair. How much more do they require, is it 25 percent more?

 

[DavidA]

   
I think it largely depends on what kind of music you prefer. Nothing to do with amps, in my experience. With properly recorded audiophile grade stuff (acoustic/jazz/classical) HD600 sounds just right, whereas HD650 is more satisfying with lower fidelity stuff like pop/rock/metal due to more bass presence and slightly tamed upper-mids/treble.

Really didn't like classical on the HD-600, sound stage to constricted and the imaging wasn't quite right to me, I usually only listen to classical on HD-800 or SR-009, and sometime T1 gen1.  Acoustic, blues, some jazz l usually listen with SennGrado, RS2e or LCD-2, and for jazz, rock, classic rock I usually listen with HE-560 or HD-700.
 
While I don't consider all easy listening, pop, Kpop, Jpop as lower fidelity I agree with your point its probably why I like the HD-650 for them.