[redrich2000]

Update: they're MUCH better out of my Lyr 2 (shock horror!)

 

[redrich2000]

So, full review time... it will in relation to the 6XX because I think that makes the most sense. My 6XX is about 6 months old and has been fully modded according to the most popular modding guide. That is, removal of the spider cage from the back of the driver and application of damping material to the back of the driver and housing. Google or PM me if you want more details. The mod was a surprisingly good improvement. It tightened everything up, increased clarity, space and separation. The effect is across the spectrum, but it is most obvious in the upper bass and lower midrange, where the 6XX needs some cleaning up. I don't have the quarter mod installed. I expected to do this and prepared some foams before the cans arrived, but I didn't think they needed them. Although I have a suspicion I might move to them in time once the pads wear-in more and clamp-force reduces.

About me... when I started on this journey almost 15 years ago, I tended to go for cans with a reputation for being brighter. The Koss A250, Sony SA5000, Ety ER4 etc. But I borrowed a HD650 from a local head-fier and was seduced by the beautiful rich, smooth warmth of them. I had thought cans like that were less detailed and therefore inferior. But they taught me that the details are there, they're just not as in-your-face. I still love my A250, but I've modded them a bit now to improve the bass and tone down the treble. But the 6XX is my daily driver.

I'm listening using iMac > Roon (ALAC/Tidal) > Topping D30 > Lyr 2

On to the 660S...

Build quality/Aesthetics: There's very little to say here. The HD650 is very well known by now. The 660 is a matte black version, almost indistinguishable from the MD 6XX. I really like the build and aesthetics myself. It's not premium but tank-solid and stylishly understated.

Comfort: Again, very similar to the other family varieties. The pads are a bit more spacious due to steeper inside walls and so the fit around the ear is roomier. I've never had a problem with the clamp of the 6XX, the 660 is maybe a touch looser, maybe.

SQ: The first thing to say is that the 660 was MUCH better out of my Lyr2 compared to the FiiO A5. These really benefit from the tube smoothness and warmth, much more than the 6XX IMO. In general, they have a strong family resemblance to the 6XX. They essentially sound like the same headphones, but with a tweaked filter, if that makes sense. It's a significant tweak, which changes the character quite a bit. I agree pretty much entirely with Tyll's review on Inner Fidelity. Although I'd be less critical overall, probably because I have owned the 6XX only a short time and so am less invested in their character.

As Tyll says, the 660S is a slightly leaner and sharper across the spectrum. They are more spacious and airy than the 6XX. The detail is sharper and more aggressive across the spectrum. This was to the point of being harsh on the A5, but on the Lyr2 it's toned down. The treble has more sparkle but to the point of very occasionally being too hot and splashy. If the soundstage is wider on the 660, it's not by much. My sense is they give the impression of more because there's more space, but I guess that's essentially the same thing anyway.

Conclusions: Out of the Lyr2, it's a toss up between them for me. It depends what your preference is. With the 6XX you get the legendary buttery rich smoothness. With the 660 you get leaner and sharper with more aggression, speed and sparkle. I think I probably preferred the 660 for distorted-guitar-based rock genres (Sigur Ros, Dinosaur Jr, My Bloody Valentine, Afghan Whigs etc.) With those genres you want the guitars to really scream, the 660s do this better. For everything else (jazz, classical, electronic) I prefer the 6XX. I think they could work and complimentary cans, although you could probably achieve similar with something that's more of contrast style-wise.

Given the relative prices, the 6XX is by far the better value proposition (indeed it would have to be among the single greatest audio bargains ever). If they were the same price, I'd still go for the 6XX, but I could see I lot of people preferring the 660S.

Once again, huge thanks @White Lotus for organising this. We should do more of these, with our own gear if we can't get review units.

 

[Brooko]

@robthemac - PM me your address and I'll get these on their way to you.

Just finished up my notes - will impressions a few days before I get everything in order to post though.

Build almost same as HD600. Modular design almost the same. Drivers different. Very comfortable, and like the black matte finish. Like that Sennheiser included a 4.4mm terminated cable - but wish it was shorter. Compared to HD600, I found the HD660S a little warmer through the mid-bass and lower mids, vocals sit a little further back in the mix, and the HD660S bass seems better defined and slightly more pronounced. HD600 has more euphony with female vocals. Of the two - subjectively the 660S seems a little more balanced. Both definitely members of the HD6-- family though. Sounds like the HD660S has a little more lower treble (bit more sparkle in the upper registers).

After a week with them, I must admit that I really rather like them, and if I could do a straight swap with the HD600s, I probably would. Saying that though - I still like and appreciate the HD600 - I just never really thought the HD600 sounded a little thin through the vocal region before (or is it that the HD660S just sounds thicker?)

Anyway - I still think you can't go wrong with the 600, 650 or 660S - all variations on a common flavour. HD650 darkest and smoothest. HD600 probably the quickest by a nose, and leanest through the mid-range. HD660S draws between the two - better bass than the HD600, and more treble definition than the HD650.

If it wasn't for the price, I'd probably look to sell the HD600 and get a pair.

 

[robthemac]

I'm actually inconveniently out of town for the next two weeks... I'm not quite sure what to do!

 

[Brooko]

Well as long as our friend Mr Lotus and Sennheiser have no problems, I can hold it here, and send it along as soon as you are back.

Paul

 

[White Lotus]

Go for it mates. Keep me in the loop.

Thanks.

 

[robthemac]

Cheers!

 

[Brooko]

On their way to Rob - tracked and sig required.

Working on review - and will complete once back from latest biz trip

 

[robthemac]

Received safely.

This is an interesting one... Will write a full review hopefully this evening. I think taking the HD-660 or the 650/6XX is probably a matter of personal preference.

 

[Brooko]

Hey Rob, if you can volume match easily - try switching between the 660S, 6XX and 800S. It’s quite an interesting exercise. Would be curious to see what you think of the 660S vs 800S.

 

[robthemac]

The first thing I though when I put on the HD-660S was 'Wait, is this the HD-800S?'

Doing the comparison now....

 

[robthemac]

First impressions from direct comparison between the two (using different DACs/amps to enable more prompt switching):

You can certainly hear the family resemblance. HD-800S has more top-end sizzle and detail. The brush-work in Norah Jones' 'Come Away With Me' stands out more. I prefer female vocals on the HD-660 though. Listening to 'Landslide' by Fleetwood Mac. Sounds more full and natural on the HD-660S, even if you get a bit more of the reverb detail on the HD-800S. I prefer the bass of the HD-800S - more extension and definition, compared to the (relatively) hefty mid-bass of the HD-660S.

 

[Brooko]

Yep - you're hearing it exactly the same I have been Rob. Surprised me they were quite similar though - and more so than the HD600 or 650.

 

[White Lotus]

I heard it too. It definitely feels like the HD800S and HD660S are all cut from the same cloth.

 

[SilverEars]

Man, the tour would have been more interesting with addition of HD58X in the mix.