[GearMe]

Sure, but that can’t explain the kind of discrepancy we see in those graphs, can it?
OTOH those graphs would certainly explain the differences that people have reported hearing in early and more recent examples......

the DIY-A-H graph certainly 'looks' more like what I heard when I had them...

 

[Ichos]

Well probably the 150Ohm driver don't scale well with OTL amps.
I think this is the first HD6x series headphone that is better enjoyed with SS amps.

 

[DavidA]

Well probably the 150Ohm driver don't scale well with OTL amps.
I think this is the first HD6x series headphone that is better enjoyed with SS amps.

Agree with this

 

[Ichos]

I wonder though how it will pair with a good hybrid amp.
Unfortunately i don't own the Mjolnir 2 anymore.

 

[DavidA]

I wonder though how it will pair with a good hybrid amp.
Unfortunately i don't own the Mjolnir 2 anymore.

I'll ask my friend Tomo in Japan who has a Liquid Glass amp (best hybrid amp that I know of) to see if he can give me some feed back on how a HD660S (not sure if he has one) sounds on it. When I had his Liquid Glass for a few months it was quite an impressive amp and could drive almost anything but the tubes used played a fairly large part in how it would pair with some headphones like the HD800, T1gen1, HE560 and K812.

FWIW, to me the HD660S sounded fairly similar on my Lyr2 (Telefunken CCa or Siemens Lorenz) and straight out of my S9 phone which is why I don't consider it to "scale" much IMO but it does sound far better than my HD650 or HD58X out of my S9 phone which is what I think makes the HD660S so good, but still over priced after hearing a second HD58X (much less grain than mine) that was fairly close for 1/3 the price.

 

[nocturaline]

Well, after some more listening and comparisons, I have concluded the following - which echoes the few last comments on this thread:

With the Woo WA2 (OTL), the 650 has a sweetness that the 600S doesn't possess. In comparison, the 660S sounds a little bit cold. It's still quite good, but not as good as it should be. So, avoid the 660S if you have an OTL.

With the Sony ZX300, balanced, the 650 doesn't sound bad, but is not very exciting. It's a little flat and lacks separation. The 660S, on the other hand, is majestic, powerful, and fun. I'm sure that the lower impedance helps a lot.

I love them both, but since these days I'm only listening to the ZX300, the 660S is the better choice. I bought it to work with that DAP in the first place, so it's a win.

Now, I must confess there's something I truly hate about the 660S, and it's not sound or comfort related; it's the insane length of the 4.4 cable! Come on Sennheiser, the 4.4 is mainly to be used with a DAP. Do I really need a cable that's 9 feet long? Consequently, I'm going to order a 3-foot Michanikos cable from ZMF. It's should slightly change the sound in a good way, and will be the right length for a portable DAP.

 

[pietcux]

I like the new improved bass, it feels and sounds kinda effortless. I listen to a lot more micro detail like on the HD650. No annoying treble peak so far. Sound like a big success from Sennheiser.

Let me quote myself. This post was done on 20-OCT-2017. My first impressions. Good decision to keep them, Mike.

 

[Krutsch]

I have listened to the 6xx on the ZX300 and I can tell you with certainty that the ZX300 cannot handle the 300 ohm impedeance of the 6xx, neither could my dx150, or the WM1a when I had it. The only DAPs i can say could drive the 6xx well with fulness is the Hiby R5 and R6.

I listened to the 660s for a good amount of time today on the NW-A35 and it was driven quite well. It was a really nice marriage those two had today.

My daily work rig is an NW-A55 and the 660S. While it does work, I ended up getting a 4.4mm --> 2 x 3.5mm balanced adapter and connecting the Walkman and 660S via its balanced cable and a Sony PHA3 DAC/amp.

Now *that* combo can properly drive the 660S.

 

[Krutsch]

...A bad review from Tyll is the kiss of death. Now that he's retired I don't think there is anybody else with that much power over the fate of a headphone.

And that's a very good thing. I think most of us have figured out by now that we all perceive sounds differently.

 

[equalspeace]

I think there was a revision done to the sound on these headphones at some point. Original pair i have was bought used off of ebay. It’s got 2018 drivers (i disassembled and checked). Anyway, i bought a new pair and checked the drivers and they are from 2019. Both pairs aren’t completely burned in. Old pair was used 3 times supposedly and I put maybe another 35 hrs on them. The new pair got over 50hrs of burn in. Long story short they sounded so different. The newer pair with current drivers sounded less precise, a little slower and there was a bit less midrange texture, less sparkle in the treble regions overall, and maybe slightly worse imaging. The new pair got returned. Also word to the wise, the new pair did not have the made in Ireland badge on the headband. My older pair does. Just thought this should be put out there, as it was mentioned last week.

 

[Deftone]

No retuning as far as I'm aware, all the 660S ive heard sound the same. Mine are early set made in Ireland and I've had them for about 10 months. My friends and the ones in stores are the same wether made in Ireland or romania just the change in pad thickness.

Unless there's definitive proof I'm staying with its Always been the same headphone.

 

[Ichos]

I have heard three pairs of 660.
The first one was about one year ago my review unit made in Ireland.
The second one about three months ago a three days loaner unit also made in Ireland.
Both were brand new and I was the first person to use them.
The third is the one I own brand new fresh out of the Romania factory with the new looks.
All three sounded exactly the same.

 

[coletrain104]

anybody try these with dekoni elite velour? FR looks so good on HD600, but I've always held out since HD700 that this driver is more technically adept. I don't like the roll-off in bass comparatively, hence the pads question, as they bring up the bass on 600.

 

[Mike F]

I think there was a revision done to the sound on these headphones at some point. Original pair i have was bought used off of ebay. It’s got 2018 drivers (i disassembled and checked). Anyway, i bought a new pair and checked the drivers and they are from 2019. Both pairs aren’t completely burned in. Old pair was used 3 times supposedly and I put maybe another 35 hrs on them. The new pair got over 50hrs of burn in. Long story short they sounded so different. The newer pair with current drivers sounded less precise, a little slower and there was a bit less midrange texture, less sparkle in the treble regions overall, and maybe slightly worse imaging. The new pair got returned. Also word to the wise, the new pair did not have the made in Ireland badge on the headband. My older pair does. Just thought this should be put out there, as it was mentioned last week.

Are you sure it's not just a pad issue? Did you try to exchange them? The sound changes considerably when the pads start to break in. Straight out of the box they sound more as you described. I feel partly responsible for this because I was the one talking about a revised version with a different sound, BUT, if that did happen I was assuming that it happened very early on, long before the move to Romania was made. I really don't think that has anything to do with it (although it's tempting to think that something may have happened when the move was made to a new factory, it's extremely unlikely), and, honestly after looking at more FR graphs I'm now very unsure that anything can be objectively concluded. FWIW the HD660S that I listened to at the store was made in Ireland and I couldn't hear any difference between them and mine. Also, ultimately, if Sennheiser did make any change to the HD660S it would seem highly unlikely that the difference would be as you described above (i.e. generally worse). Sounds far more like a 'brand new pads' issue to me.

 

[GearMe]

Honestly, I think there's been some 'bad' ones out there. My Senn Renewed sounded a lot like @equalspace described..."less precise, a little slower and there was a bit less midrange texture, less sparkle in the treble regions overall, and maybe slightly worse imaging."

I was very excited to be able to pick a Mfg Refurbed unit for a nice price...and very bummed to return them.

Will go with brand new when the prices drop