Superlux HD661

Something about me before the review:

I started live mixing as of April 2017 every Sundays. Still quite the amateur but I am quite learning about live mixing
I am formerly a bassist.
I prefer fun-neutral sound signature. A some sort of V-shaped or M-Shaped Frequency response to help me hear the low-end and the high frequencies. I am quite the detailhead, but I would love at least little amounts of soundstage and imaging to at least have some panning details to be clear.

Build Quality

These headphones are like Toy-Grade build like this is like meant for kids handling as far as the feel in the hand. This could quite survive in the hands of the klutzy kids. They feel like premium Auldey Toys in the hand. I have Nothing to complain about the build so much that these Superlux Headphones could quite rival the build of Sony and Audio Technica headphones. The pad replacement is easy, just a twist and pull will remove the pads, so at least they are moddable. The 3.5mm Male jack on the headphones may be something that people hate, but at least for me this system is way better than the Audio Technica and Shure's Locking 2.5mm to 3.5mm because Headphone extension cable is easier to find at least.

Comfort

These headphones are light on the head, but they quite clamp hard. You need to box-stretch these cans before using these. Pads are quite stiff, so you may need replacement of pads if the comfort really grits you

Sound In-Depth Review

Before burn in:
I was just testing this out on a local store(and bought it the same day) using the phone. I was quite interested at my first impressions because they are quite detailed and they have soundstage and imaging that is decent for a closed set of cans. Quite comfortable to listen still, not the most sibilant stuff.

When I brought it home and plugged it into my FiiO K1 DAC/Amp, they showed their true unburned nature. They are Treble Cannons, with the recessive midrange and recessed bass. So, as a tip, DON'T USE THEM EARLY WITHOUT BURNING IN

After Burn in:
I burned the Headphone Drivers 8 Hours at first. Noticed the treble recession like it is Night and Day.
Quite Sibilant still, but still quite unlistenable to some Tracks like Ai Shinozaki's Waruineko(Where the headphone shows the unforgiving sibilance of her shrill voice). I let them burn in for another 8 Hours and they become the perfect neutral cans. I will review them as of how they are now after the 16 hour burn in.

Bass:
The bass is good. Not the fastest but at least the details of bass tones are heard clearly. Mid bass can be clearly heard but it can be quite a struggle at some levels especially when there are electric guitar leads that also come with the song. It can rumble once it gets to the sub bass, but sometimes it is quite teasing to the ears especially on EDMs. One thing is for sure. The HD661 has a clean bass, no Muddiness at all.

Mids:
Mids are slightly recessed after the burn in. but they are decently audible for the details to come up and quite accurate enough for my monitoring tasks

Treble:
This is one of the main reason you will either buy or avoid buying this unit(unless you are into modding). They are quite strident. This headphone is unforgiving to shrill female vocals. The Crash will Crash unto your ears. The sibilant sounds will surely pierce your ear drums. The Electric Guitar leads are intimate with this Headphone, so it gives rock, and heavy metal justice to their recordings.

Conclusion:
I purchased these for $39(They are the only unit left). They are quite the economic monitors. I would recommend these for starters in the live mixing. For musicality, I would also recommend it but just be warned of the Treble cannons, and some comfort issues. Acoustic Modding Work is quite interesting with these since they are quite modular on the pads but the insides has less room for modding work so for sure they cannot be the next T50RP in terms of modifiabilty. One thing is for sure, The Price to Performance Ratio is excellent for these monitoring cans.

I will have to deal with the pinkiness of these monitors, I really want to be lowkey with black, white or gray color(They are the only ones available, but the sound really grits my heart). But who knows, girls might find me sexy with this pinky

Notes:
Some modding tips.
https://www.head-fi.org/f/articles/superlux-hd661-anti-sibilance-and-comfort-mod.19634/

Buying:

I bought these new from a UK ebay shop (kmagencies) for £22.50 which is US $35.95 or €26.56. Price included next day live tracked delivery with the delivery timed accurately to within an hour slot so if you're in the UK and want a pair of these this has to be both the cheapest and most convenient deal you will find.

Some context:

I have had some bad luck with full size headphones:

My Sennheiser HD 500 died after about 10 years. I bought Sony MDR ZX700 to replace but they have a design fault which leads to pinched internal cables and are doomed to fail, which they did. I tried some AKG 451 but they were muddy and a bit booming and had obviously recessed upper mids so I took them back and got a refund. So for a long time I've been using IEMs and Koss KSC75 even at home but I am really bored both of sticking stuff in my ears and of headphones with no isolation (I live by a busy road). Last week I bought Sennheiser HD215-II but took them back after a couple of days because they gripped my ears uncomfortably, were incredibly hot and sweaty and, despite the specs, were not sensitive enough to use without a powerful amp. I got a different model as a replacement but they were faulty and I got a refund the same day and went home feeling very fed up indeed with budget closed headphones due to poor design, poor sound, poor manufacturing quality and the hours I'd wasted.

What I wanted is pretty simple: isolation, comfort, enjoyable sound, compatibility with a small headphone amp and maybe even my personal players. None of this has to be perfect, only unobjectionable but it had started to look like a mirage, at least without spending hundreds. I had read reviews of various Superlux products including the HD661 but noticed most of the very enthusiastic reviews that had driven big interest were by a handful of people selling them and this wasn't always made clear. I also saw that reviews by people who do their own measurements and analysis do not correspond to the promotional reviews but do tally with customers reporting less satisfying experiences, so I dismissed the Superluxes as stuff to avoid. However I saw someone on another forum describe how he makes a correctional filter which he solders into the headphones and tames the highs and that the HD661 can sound really nice. This was not someone who claims nirvana achieved after listening to some mp3s on his new 'phones so I paid attention. I'm not skilled in soldering but I can definitely use a parametric equalizer to do the same thing. So I decided to risk a little money and hunted around until I found the cheapest deal in UK and bought a pair of black Superlux HD661.

Features, design, fit etc.

In the box you get the headphones, a short straight cable, a long straight cable, a cable clip, and a 3.5mm to 6.5 mm adapter. Some reviewers seem excited by the accompanying bag. It's pretty nasty, being made of the type of cheap synthetic material that might be used to clothe a child's doll. It has no padding and is basically ugly, unpleasant to the touch and pointless.

You might have read that these headphones clamp very hard. This is true but is fixed easily by just pulling the things apart a bit wider. They stay wider. I have a pretty big head, about 23" around, and have been wearing these for many hours today (maybe eight) and don't have a problem with them. They are quite light and the bits that touch the head are very flexible and don't press. The shape of the cups is very good as it is elongated. I found small round circumaural headphones intolerable because they squash the ears but ones with a more rectangular ear cup are very comfortable even if snug like these. The pads are better than I expected and I haven't had sweaty ears even after hours. By comparison the budget Sennheisers I tried last week started cooking my ears after just a few minutes.

The cable enters on the left and the signal is carried to the right driver by the metal rods that make the headband. I've had various headphones and IEMs fail due to lousy cables and lousy cable routing so I like anything that makes this less likely. The cable on the left is only about an inch long and you attach either of the main cables to it. Everything is standard 3.5mm jacks, no proprietary nonsense. The cable clip prevents the attached cable from coming loose. It doesn't seem to me like it would come loose and anyway I'd prefer a cable to pop out than the headphone to get tugged but the clip does work and supplying it is a nice touch.

The sound:

Sources:

flac derived from CD and played with:

PC SPDIF to Yamaha HT receiver
PC to FiiO E7 USB DAC/amp
iRiver H140 (Rockbox) headphone out
iRiver H140 (Rockbox) line out to FiiO
Sansa Fuze+ (Rockbox)

The iRiver can drive these easily and the Fuze+ drives them OK but it is at or near maximum volume to do so. The FiiO has no trouble, nor does the Yamaha amp.

Sit back and press play:

Ouch! It's OK until you hear a powerful female voice or a violin or lead guitar or similar powerful high pitched sound and then it is piercing, harsh, and sibilant. It's really bad and if you ever saw the innerfidelity review of other Superlux models you might recall Tyll Hertsens saying it was like listening to good headphones through razor blades. Great description! Probaby the same drivers do duty in lots of the Superlux products with the sound differing a little according to the type of enclosure and the impedance difference of the other components.

I also thought the sub bass was limited and the bass overall was too polite and lacking the small boost that helps with headphone listening. I also think that Superlux's own frequency response charts have to be interpreted as being promotional material first and measurements second (that's the polite version).

Anyway in other respects I liked the headphones. They isolate well, they are pleasant enough to wear and apart from the terrible high frequencies the sound seems quite open and dynamic with detail and real clarity (not the same thing as the harsh highs). So I got to work with parametric EQ in Rockbox and so far have arrived at this:


edit: I think these revised settings are better:


I'm definitely not claiming these settings as anything special or definitive and they will inevitably change with extended listening and familiarity but so far it achieves some important things:

No more feelings that my ears are about to split and bleed from screaming razor blade attacks.
A more natural upper midrange (female singers still have natural presence and timbre but no longer sound harsh and edgy)
A bit of boosted bass and some warmth (the bass boost is a matter of taste whereas the adjustments to the higher frequencies are a matter of necessity, being remedial).

I also got as close to this as I could using alsaequal on my desktop.

The headphones now sound truly enjoyable. Naturally with extended listening I'll make some adjustments and notice other qualities good and bad but for the moment I've been listening to a variety of rock, orchestral, choral and instrumental music and enjoying these more than the other small closed headphones I've tried recently. I think this might be the first cheap closed headphone I've heard whose sound doesn't keep reminding you that it's closed amd cheap - very refreshing.

Conclusion:

I think my Koss KSC75 will be getting a bit less use and my various IEMs can go back to only being for urban and travel use and my ear canals can finally have a break.

I would strongly caution against buying these if you won't have the facility to either modify them physically or to use them with an equalizer. However if either of those is practical for you and you want some closed, circumaural headphones of reasonable sensitivity then these are a very attractive bargain giving you a more enjoyable experience than some closed headphones that cost two or three times more. Comfort is very good, they work well with a small amp or more powerful personal player, and the sound can be made very enjoyable. Also cheap, cheap, very very cheap

 
Packaging
 


 
Having received two other Superlux headphones in the past I wasn't expecting much outside of a no frills cardboard box. While I wasn't completely blown away, Superlux definitely took some notes from other companies and made the packaging much more appealing than the 668b or the 651. The 661 come in black box with red sides, what's interesting though is that on the front right half the 661 are exposed by a plastic window. The left side is a profile picture of the 661 in a glossier paint than the matte black, HD661 is also in this glossy print in black. Under the HD661 is says "Professional Monitoring Headphones." On the back Superlux has printed in white lettering the specifications and accessories in English as well as 3 other languages. 
 
The front of the box flips open to expose the headphones that are laying on red cloth, which turns out to be the carrying pouch for it. Also included are 2 headphone cables (1m and 3m), a 3.5mm to 1/4'' adapter and a cable clip. 
 
I'm very impressed with what Superlux has done here. The box is very appealing from a consumer standpoint, it isn't flashy yet it will catch your eye. The included accessories are a very nice touch as well, it's rare to see extra cables and an adapter in a $50 headphone package. I don't have one complaint about the packaging, well done Superlux.
 
Design and Build Quality
 



 
Superlux is known for making some great sounding headphones that are very hard to beat for the price, one thing no one has ever praised them for is the build quality though. With the HD661 I can honestly say I'm impressed with the build quality for the price. Everything is plastic, but has a very sturdy feel to it from top to the bottom. 
 
The wing system makes an appearance here in typical Superlux fashion. Thankfully it's been redesigned for some more flexibility and comfort in comparison to other models like the 651 and 668b. Unfortunately the wing system is still the worst part of the design, even though they've re-designed the wing they're still rigid and uncomfortable. I will say that they do a good job of allowing for fit of all head sizes though, which is necessary since there's no way to adjust the size of these. Holding the two sides together are two plastic pipes which flex decently with no worry of them cracking or breaking for those with larger heads, unfortunately though since they're plastic they can't be stretched to reduce clamp. 
 
The ear cups each have raised chrome text that says Superlux which stands out on the very glossy black paint. Below that the model number is printed in grey with an indicator, or lack of, for which side is which. What I mean by this is that only on the right ear cup is there an indication of which side is which, an odd choice. Another odd choice is that the ear cups can swivel, but not sideways, they can swivel vertically completely to turn the driver out. The ear cups are fitted with thin leather pads that can easily be taken off. On the left ear cup a 3.5mm male plug is exposed to allow the included cables to attach which is a nice touch.
 
Once put on the 661 aren't very comfortable. Part of this is the wing system being rather rigid creating some down pressure of the headphones, the other part is the clamp. The clamp is similar to that of the Sennheiser HD558, but the pads on the 661 are more thin and rather rigid. Due to this I wasn't able to wear the 661 for extended listening. They aren't terribly uncomfortable, but I couldn't wear them for more than an hour or two. I did find that the 661 worked decently for portable use though in non-noisy areas. I never worried about them falling off and they don't leak much noise. I wouldn't use these in a library or a train, but for a quiet walk around the neighborhood they work well.
 
The 661 aren't going to win comfort contests and I wish they would ditch the faux Audio Technica wing design in favor of something more comfortable. The build quality is a nice step up though from the 668b. The 661 feel solid with no creaks or worries about them breaking, I feel they could even stand a few drops with no worries. I also said that the paint was glossy, but I don't think I can stress it enough, it's almost able to be used as a mirror, take that as you will. The 661 also come in a variety of colors which should allow anyone to find a style for them.
 
Sound Quality
 
As always I gave these 50 hours of burn-in time. No significant changes were noted during burn-in.
 
The 661 have a bright, slightly aggressive, but balanced sound to them. They're very musical headphones that manage to blend that with good detail and not be boring to listen to. The lows are fantastic here with good upper and mid bass impact with good extension which gives kick drums a good thump. Unfortunately when it comes to the sub-bass though I find myself wanting a bit more. The bass extends well enough, but it's almost teasing as I can't feel it, the rumble just isn't there. The bass is rather quick though, keeping up with the quick fluctuations in James Blake's "Limit to Your Love," which isn't an easy thing to do.
 
The mids have a nice intimate warmth to them with excellent presence. I honestly find the miss to be almost perfect here with good clarity and a nice slightly forward feel to them. To put it simple, rock music is an absolute joy to listen to with these, I find Coheed and Cambria and At The Drive-In to be hard to not listen to through these. The highs are the focus here and with great extension and sparkle. They are clean and detailed with good presence to them while managing to not cause fatigue.
 
Every aspect of sound is well represented here and while the 661 is a tad bright, that doesn't mean the lows are lacking, unless you're a bass head that is. It's rare for me to find a headphone like this with excellent lows, but great highs and mids that aren't recessed. Part of what makes these so fun to listen to though is how the music is presented. The music has an intimate feel to it and has an aggressive forward edge that makes alternative rock come to life. The sound is actually presented similar to how the Grado SR80i present sound, but less in your face with better instrument separation. Another thing that impresses me is how great these sound from an iPod despite it's 68 ohm impedance. These are very efficient, more so than the 668b even. 
 
Onto the songs:
 
At the Drive-In - 198d
This song has great dynamics to it with it's soft intimate verses to the heavy intense bridge. The 661 handle this song almost perfectly. During the verses the hushed sound of the song is handled perfectly with each instrument able to be heard with great clarity, but the restrained sound of each is heard. When the chorus hits the guitars explode, the cymbals crash, the vocals come to life. The dynamics of this song are handled perfectly. The guitars have great crunch to them, and the vocals sound intimate as if I'm in the same room.
 
Sara Bareilles - Vegas
This song has a nice bluesy vibe to it as well as a talented singer. Right away the HD661 expose some mastering problems with the bass being a bit too boomy, it actually hurts the song a lot more than I thought. Moving on though Sara's voice sounds good, slight sibilance here, but it's more of a recording issue than an issue with the 661. While the 661 aren't incredibly detailed they certainly expose some bad mastering here, take that as you will, but I don't like this song through these.
 
Sufjan Stevens - John Wayne Gacy Jr.
Hushed vocals, a fuzzy acoustic guitar and a winterized sounding piano are the primary culprits here. I have to say it sounds wonderful the piano weaving in an out giving a cold vibe to the song with the guitars bass notes adding some warmth to the song. Sufjan's vocals sound incredibly smooth here. This is a song I've listened to hundreds of times and I am enjoying it a lot through the HD661.
 
Hot Chip - I Feel Better
A cheesy electronic mock track with a thumping kick drum and filled with synths and auto-tune. This song carries a lot of energy and definitely relies on every instrument to come through clean and with authority to sound good. The bass is thumping more than sufficiently thanks to the mid-bass impact. The synth sounds full and fulfilling as it repeats itself. The vocals are clean and intimate. This song is just living through these headphones, it sounds absolutely fantastic. I'm nodding my head and can't stop, thumbs up here.
 
Pretty Lights - NIN vs Nirvana vs Radiohead
This song has a nice blend of panning, sub-bass and atmosphere to it. The HD661 aptly handle this song. The panning is done well, not as 3d as the Brainwavz Beta, but it has some depth. The bass has nice extension, but I don't feel the rumble, this is a disappointment because it takes some of the raw sound of the song away. Overall the song is very clean sounding though, great production value and it comes through with the HD661.
 
Conclusion
 
The HD661 are an excellent addition to Superlux's already impressive budget line up. The HD668b will suit those who want a more flat sound with a tad more bass response while the HD661 will cater wonderfully to those who favor treble, but still want a clear balanced sound with good bass response. The build quality is great for the price, though I wish Superlux would consider a leather band or another option in place of it's wing system. The Samson SR850 are much more comfortable than the HD668b, for example, because of that and are still able to be found for the same price. Either way Superlux seems to have found it's niche, making excellent products at a budget minded price. I highly recommend the Superlux HD661 for it's suggested retail price of $50 for it's versatility though I have to say I highly enjoyed alternative rock the most through these.
 
For those looking to purchase these, unfortunately they are a bit hard to find. If you e-mail Superlux though I'm sure they will assist you in finding a shop or a place online!
 
Come see more pictures of the HD661 here!