I’ve been trying to do quick reviews over the last few months to get through some of my backlog, but … my “quick” reviews are increasingly becoming downright un-quick and growing to rival some of my “full” reviews, so I’m going to try a new thing here to get it a little more under control.
These are going to mostly be things that are a) very niche, b) are mostly unavailable, or 3) that I really don’t like; AND that are not interesting enough to be to justify doing a quick or full review. I’ll still do some reviews of things that fall in those categories if I really like them, they are “important” in the context of the headfi community, or I otherwise just want to talk about them at length.
I’m sure the format will morph over time. Just for my own sake, this will consist of the most recent, and then the rest in alphabetical order. If I remember to keep that pattern.1
Up next: the Grell x Drop OAE-1!
Mini-Reviews:
Most Recent:
Grell x Drop OAE-1 Review
(Reviewed May 1, 2026. MSRP $349, currently out of stock new after Drop’s closure. Paid $99 in November 2025.)
[Tl;dr: Definitely one of the most odd headphones I’ve ever tried. I don’t hate them the way that a lot of folks do, and there are the occasional tracks that they work incredibly well for. That said … they’re more of a novelty than a headphone I’m going to particularly want to listen to. I’m curious to try the second generation OAE at some point, though it’s currently retailing for around $600.
I’m not going to recommend these to anyone; if you’re the kind of person who wants to buy these, you already know that you are. If you’re on the fence, you really shouldn’t. That said, if you know me in real life, these are 100% worth a listen sometime just to have experienced it.]]
Cost-agnostic: 2 out of 10 Denalis
Cost-sensitive: 1 out of 10 Denalis (MSRP), 4 out of 10 (at $99)
The Basics. The OAE-1 is a passive, open-back, dynamic driver headphone. It’s the first release from Grell Audio, a new company founded by Axel Grell after leaving Sennheiser. It’s not particularly hard to drive, at 38 Ohms of impedance and a reasonably high SPL of 106 dB/1Vrms, and they weigh in at a reasonable 375 grams.
Axel Grell is the former Sennheiser engineer who invented some of that legendary company’s most legendary products, and arguably kicked off the audiophile headphone revolution in the 90s by making things like the HD 580 and HD 600 both excellent and affordable. When he left Sennheiser in 2019, a lot of folks (including myself!) were really curious to see what was up next for him. As it turns out, it was starting a new headphone company and making some … let’s call them bold plays to re-revolutionize the industry. Enter the Grell OAE-1. So what is it?
There are a lot of ways to approach explaining this, but the short version is this: for a long time, headphones have been designed using a thing we call the “Diffuse Field”,5 to simplify it way too much, it’s basically the idea that headphones should be tuned to sound like we’re listening to speakers in a space where sound arrives from all directions at the same time and at the same volume.6 Grell takes a different approach with the OAE-1 with both physical design choices (drivers facing backwards at the ears) and the frequency response (the tuning of the headphone) to try to emulate listening to a pair of speakers directly in front of you. It’s interesting, and different and … well, I’ll leave it to you to decide if it was worth it.
Technicalities. These are a hard headphone to categorize because they’re … weird. They’re just weird. The soundstage is wide but also just sounds wrong sometimes; “Chan Chan” is my usual test track for soundstage but the opening guitars sound very wide out, behind you, and muffled. The organ on “Calls” pans wildly; I’m not sure I’d realized how much that is moving around in the mix until the first time I put these on. The rest of the mix is pretty well placed in space, but oddities like that are not uncommon with these headphones. Detail retrieval seems fine but not exceptional, and the timbre is … also weird. Flat sometimes, metallic other places, and just … strange overall. Microdynamics are great; the bass is tactile and physical and it’s one of the better versions of the bass bell tones on “Angel (Blur Remix”) I’ve heard … even if the treble bell tones sound … weird.
Sound. The bass is a bit overwhelming on the OAE-1; to the point where it can be very difficult to hear midrange. It’s not uncommon for swollen mid bass to swallow the lower mids on a pair of headphones, but this is the first time it’s also eaten the rest of the midrange including some vocals, particularly male vocals lower in the register. The bass is generally well-resolving and clear, though, with pretty good extension down into the sub bass and very little splatter even on tracks like “Violence” or “Superpredators.” The mids are often timbrally weird, with voices sounding just a little bit off, and particularly male vocals seem to suffer from the over-blown bass tuning. Depending on the track, the treble is either excellent or really, really off, with very little in between. Always well controlled, though, even if even I want to add in a little treble via EQ.
Here’s how my unit measures:
Yeah, that looks about right. What a weird headphone.
To be fair, there are some tracks that they work really well for. “Garcia Counterpoint” is an example where the wider stage adds some really interesting impact, and where the timbral issues aren’t particularly apparent. Weirdly, something like the remaster of The Clash’s “Straight to Hell” sounds incredible with these headphones. The percussion is super wide out, and Joe Strummer’s voice works perfectly.
EQ. I mean … EQ does fix SOME of the weirdness of these headphones, but at the cost of everything that makes them unique. The Oratory1990 Harman Target preset brings them back down to earth (especially that bloated bass), but I’m not sure I would choose to use it. If you’re putting this headphone on, you want a bit of strange. Some more ambient tracks also seem to work reasonably well, as long as they aren’t particularly vocal-heavy.
Build. These are a somewhat perplexing build. The cups and the band are pretty well padded but somehow not particularly comfortable? The pads are a nice soft velour but the memory foam inside the pads is so stiff that they’re not the easiest to get settled on my head, and a seal can be challenging around glasses. They’re definitely solidly built, and I appreciate that they don’t feel cheap the way that some of Grell’s prior designs (*cough* 6X0s *cough*) feel, and I actually like the way they look.
The cable is both pretty cool (balanced capable and can be inserted into either cup, giving you the same flexibility as the HD 490 Pro) and annoying (proprietary 3.5 mm that is … not particularly easy to get fully inserted in the rubber gasket around the jack), and it’s made out of a particularly not-annoying cloth, which is pretty cool too.
Overall. So did Axel Grell’s big swing work? Meh. You can be the judge of that. At least it’s interesting, and different, and was a big swing. The OAE-1 wasn’t particularly well received when it was released, but the second version is out now and I’m curious to give it a listen at some point.
As for the OAE-1 itself, it’s … weird, but I don’t hate it. In a world in which so many headphones are all just variations on a theme, I appreciate that Grell was willing to zag in a market where everyone is mostly zigging. They’re probably not something that I’ll use regularly, and I would feel bad if I paid MSRP for them, but for $99 they’re a fun thing to be able to throw on from time to time (and the soundstage is … fun and funky and unique). And very occasionally, they just light up a track.
Alternatives. This is such an unusual product that it’s hard to even know what to compare it to; it’s a sui generis headphone, and there’s nothing like it on the market that I’m aware of. There are definitely headphones in a similar price point that I’d take over them for regularly listening; any of the open-back Hifimans under $150 are going to be markedly better for regular listening (HE-4XX, 5XX, 400se, etc.). I’d definitely take the OAE-1 over the Sennheiser 560S, though, weirdly, but I wouldn’t particularly want to listen to either for any length of time. I can at least correct the OAE-1 with EQ, though, at least.
A
AKG K701 (April 5, 2026)
(Reviewed April 5, 2026. MSRP $599 currently around $165 on Amazon. Paid $125 + $25 shipping + $52 in Freedom Fees7 in December 2025.)
[Tl;dr: I’m genuinely impressed with the AKG 701; I mostly ordered them on a lark when I saw them marked down 75%, but they’re … great. Surprisingly great, with EQ. They’re potentially even competitive with the HD 600 for vocals, though overall I think I’m still taking the HD 600. They’re also incredibly comfortable on my head, both light and nicely accommodating. If you’re looking for something to enjoy vocal-focused music and don’t want to spend $300 on a pair of HD 600, or prioritize comfort over everything else (or want a comfy platform for EQ!) I commend these to you without reservation. These have earned a place on my wall.]
Cost-agnostic: 7 out of 10 Denalis
Cost-sensitive: 3 out of 10 Denalis (MSRP), 8 out of 10 (at $150)
The Basics. The AKG K701 have been a staple of the audiophile space for almost twenty years. AKG describes the K701 as a “reference-class premium headphone” and sells them for $599, though you see them on pretty substantial sale on a regular basis in the US. They’re an open-back, dynamic driver headphone weighing in at a 6X0-like 235 grams, and have an impedance of 62 Ohms and a sensitivity of 105 dB/mW, making them reasonably easy to drive, even directly from devices.
Technicalities. The K701 have a decent but not exceptionally wide soundstage, with a surprisingly good front-to-back staging and pretty good separation between instruments and layers. The detail is good but not great, and the timbre is overall pretty solid especially for vocals.
Sound. Bass is definitely on the lighter side on the K701, but really well executed, clean and precise even on splattery tracks like “Superpredators.” The warble on “Angel (Blur Remix)” is pretty good. I’d compared it to something like the 6XX in terms of how good it is at bass in isolation, though their relative recession doesn’t hold up as well on more crowded tracks.10 Mids are the strength of this headphone, with Jill Scott coming through beautifully on “Calls” (one of my favorite reproductions of her counter-melodies and background runs) and Justin Hicks’ is damned near perfect on “What Did I Do?” This may be the one headphone that out-vocals the HD 600 in some ways, though I prefer the overall tune of the 600s. The treble is definitely a “reference”-focused tune, with elevated (and to my ear, occasionally unpleasant) treble; the synths on “Clair De Lune” are a bit sharp, though Davis’ solo on “Will O’ the Wisp” mostly stays just this side of harshness.
This is a headphone that benefits immensely from EQ, though, and doesn’t surrender its character and uniqueness when you apply even a fair amount of it. Though, I will note, it’s not something I’m going to grab when I know I’m listening to something that’s treble-forward, even with EQ.
Yeah, this is more or less what I hear; more forward vocals than even the HD 600, and I definitely hear that spike at 5-6 kHz (which explains why Oratory knocks that down by more than 6 kHz in his EQ).
EQ. These are headphones that mostly don’t *need* EQ, but definitely benefit from it (particularly with a bass shelf and a little de-spicing of the treble). I’d start with Oratory1990’s excellent EQ profile for the K701, and I take down Bands 5 (treble) and 7 (3.5 kHz) a dB or two to take the edge off them.
Build. These are incredibly comfortable headphones. The pads are fluffy and just soft enough; though they feel a bit firm to the touch, they’re surprisingly accommodating when combined with the K701’s relatively light clamping force. They’re light, they flex nicely, they’re soft … this is on the same level as the HD 490 Pro when it comes to comfort. The cups are also surprisingly big and accommodate my ears, and they don’t seem to be particularly affected by head position in my measurements (with very little, and VERY consistent, channel variation).
My only build complaint: this cable sucks. It just sucks. It’s not detachable, it’s a pretty mediocre cable in terms of feel and texture, and … it’s 3 meters long. I don’t know why AKG thought this was a good idea, and it clearly wasn’t. It’s a bad cable, and it’s like three times longer than it needs to be. If you get these, get the K702 which is the same headphone11 but with a detachable (albeit mini-XLR) cable.
Overall. Overall, I’m really surprised by how much I enjoy these headphones. They’re particularly good at quiet, more sparse music, with a low end that is not particularly loud but is just very well done. And the vocals/mids are great, and the treble is … fine, but easily adjusted. I genuinely don’t know how often I’ll use these, with a wall of great open back options, but I’m glad to have them in my collection.
Alternatives. Obviously don’t pay $600 for a pair of K701s in this market and at this point. I think they’re a steal at $125, and even pretty good at the ~$200 I paid all-in. In a world in which the HD 6XX is available at $200, I’m going to take the 6XX pretty much every time (even though the K701 are more comfortable and better for vocals!), but when the 6XX are $100 more expensive like they are now … man, I’d think real hard about these, particularly if that $100 means a lot to your budget, or you’re clamp sensitive.
I would take these over a lot of things in the $100-125 price range, including probably both the HE-400se and HE-5XX; I think at the end of the day I prefer their out-of-the-box tune over the K701 but the K701 takes EQ beautifully and the level of detail and natural timbre you get out of the K701 (particularly for vocals) is quite something. I’m probably taking Sundara and the FT1 Pro at around $200 over the K701, but that’s more a reflection of how good they are at their price points than anything to do with the K701 as a headphone.
G
H
Hifiman x Drop HE-5XX (April 5, 2026)
(Reviewed April 5, 2026. MSRP $229, currently $119 open-box on Hifiman.com12)
[Tl;dr: These are a decent headphone that can be made very good with straightforward EQ, and at a great price. A little light on bass, solid on mids, and surprisingly relaxed on treble for a Hifiman. I’d recommend them to anyone looking at dipping their toes in the planar market but that doesn’t want to spend $150 on a Sundara or $200 on an Edition XS/Fiio FT1 Pro.]
Cost-agnostic: 6 out of 10 Denalis
Cost-sensitive: 7 out of 10 Denalis
The Basics. The HE-5XX was an early collaboration from Hifiman and Drop. They’re old enough to have the OG Hifiman headband, and new enough to be a Drop-branded product instead of Massdrop-branded one. They’ve been out of production for several years, and with the demise of Drop.com it’s safe to say they’re a dead-end product. HOWEVER, they are apparently for all intents and purposes a re-badged Deva Wired, so … there you go. The 5XX are a relatively heavy headphone at 355 grams (without the cable), and aren’t particularly hard to drive at an impedance of 18 Ohms and a sensitivity of 93.5 dB/mW.
Technicalities. The 5XX are a reasonably well-resolving planar magnetic with better-than-average soundstage and separation, though both are slightly undercut by some slight timbral funkiness, with some guitar tones in particular sounding VERY metallic.
Sound. Out of the box, the 5XX are a perfectly acceptable, mainstream audiophile tune, though like most headphones they benefit from EQ. The bass is a bit light, though well-controlled, the mids are fine if a bit recessed, and the treble well-controlled but a hair recessed, particularly for a Hifiman headphone. They’re a decent tune as is, though once you add in a substantial bass shelf and tweak the mids/treble a little bit, they rise to being a very good headphone.
No one on Squig has an HE-5XX measurement, so here’s mine:
EQ. Start with Oratory1990’s settings here. I ended up turning Band 2 (overall bass) down to 4-4.5 dB just because they were a tiny bit bassy to my ear, but it’s a really nice, rich tuning as is. With this EQ, I consider these a very good tune.
Build. I personally like this style of Hifiman headband as long as I’m not wearing a hat with a squatchie. There’s nothing in this price range that’s going to be amazingly comfortable, but they’re perfectly adequate, and I find that they adjust well enough to get a good seal on my head. For what it’s worth, I also think these are a pretty handsome pair of headphones with minimal Cyberman risk, though your taste may easily vary.
Overall. Overall, these are pretty decent headphones at their price point. They were a reasonable deal at their original $229, and if you can get a (well-functioning!) pair at $119 or below, they’re a great deal if you want to dip your toe in the planar market.
Value/Comparisons. I’ll take these over the 400se/400i/HE-X4/etc. family and most headphones I’ve heard under the $150 price point (including the Sennheiser HD 560S I reviewed last week). However, if you can afford an extra $40-50, the really excellent Hifiman Sundara are a better headphone in pretty much every way (except maybe very slightly comfort13). Just for fun, here’s Sundara vs. the 5XX:
Again; not Super* Review’s measurements and any flaws are my own.
- Reasonably certain I won’t. ↩︎
- I score bass, mids, and treble on a two part scale: 1-5 for quantity (5 being the highest), and A-E for quality (A being best in class, E being laughably bad). For soundstage it’s also a two part scale, with the number representing the width and the letter the separation within it. ↩︎
- For comfort/fit, my scale is A-E with A being disappear entirely into the background and E being I want to tear my ears off to stop feeling these headphones on my head. I’ve had one E: the Koss PortaPro. ↩︎
- The soundstage is so damned weird. Things are nicely separated in space, but also a lot of things are pretty far behind you which is just … odd. ↩︎
- Note; diffuse field ISN’T a headphone tuning target, it’s a calibration for microphones that we use to measure headphones. ↩︎
- Ish. Very ish. ↩︎
- Yay for 18th century economics! ↩︎
- I score bass, mids, and treble on a two part scale: 1-5 for quantity (5 being the highest), and A-E for quality (A being best in class, E being laughably bad). For soundstage it’s also a two part scale, with the number representing the width and the letter the separation within it. ↩︎
- For comfort/fit, my scale is A-E with A being disappear entirely into the background and E being I want to tear my ears off to stop feeling these headphones on my head. I’ve had one E: the Koss PortaPro. ↩︎
- These remind me a lot of the 6XX that way; if you’re going back and forth between the K701 and something else, they do sound a little bass light, but after five or ten minutes I find myself thinking “wow, this is really good bass!” ↩︎
- At least according to The Hangout; CammyFi shows a little more variation though that may be pad wear. ↩︎
- Buyer beware when it comes to buying straight from Hifiman. ↩︎
- Despite having a suspension strap, the design of the Sundara’s headband makes it harder for me to get a good weight distribution between the strap and the ear cups. As always, your mileage may vary. ↩︎
Phil's Superpower of Enthusiasm 