Rosson Audio RAD-0 Review - Not just a pretty planar

Review written by Chrono

Review unit provided on loan for evaluation by headphones.com

Introduction

Rosson Audio Design was founded by Audeze’s co-founder and former CEO, Alex Rosson. Retailing at $2,600, the RAD-0 is Rosson Audio Design’s first headphone, as well as the culmination of Alex Rosson’s experience in headphone design and sound engineering. The RAD-0 is an open back headphone that utilizes a 66mm Planar-Magnetic transducer, with no two units ever being the same as they each feature unique visual designs and are handmade in Reseda, California.

Sources and Music Used in Listening Tests

The Amplifier/DACs used in this review were the ifi Micro Black Label, Grace Design SDAC + Topping A90, and the JDS Labs Element II connected via USB to my desktop computer. For the listening tests I used music from a wide variety of genres including Rock, Jazz, Classical, Acoustic, Hip-Hop, and latin. I played tracks from my own FLAC library as well as from Qobuz streaming service played via Roon (exclusive mode).

Power Requirements

The RAD-0 is rated at an impedance of 29 ohms and a sensitivity of 98dB/mw. From my testing, I did not find them to be efficient enough to drive off sources like my MacBook or motherboard audio, but they were very easily driven by amplifiers like the JDS Labs Atom in low-gain, and Micro Black Label in ECO mode, so I think most discrete headphone amplifiers will suffice in delivering clean power to the RAD-0. 

What’s in the Box

The RAD-0’s scope of delivery includes a very tough Pelican-style, Rosson Audio Design travel case that, although not compact, will keep your headphones safe should you find yourself having to transport them. Also included is a rather nice, flexible, 8ft long, dual-sided 3.5mm to 3.5mm cable with a ¼” adapter. Lastly, you also get a Rosson Audio Design sticker.

Build Quality and Comfort

The RAD-0 is one of the most solid-feeling headphones I have gotten my hands on. It is composed almost entirely out of metal, with the only exceptions being the synthetic-leather headband and earpads, as well as the very striking, resin ear cup rings. The headphone feels extremely well put-together, and there are no squeaking or rattling in the moving parts. The only part of this build that I am not really a fan of is the sliding extension mechanism, as I worry that it might get loose over time. Aside from that small concern, I find the RAD-0’s build to be very impressive.

The RAD-0’s comfort, on the other hand, I do not think is very impressive. For starters they are a hefty headphone that, depending on the materials used, can weigh between 550g-615g. For me personally, the weight is not that big of an issue, but it can certainly be a deal-breaker and source of discomfort for others. My biggest issues, however, are the headband and clamp on the RAD-0. The clamp force out-of-box is remarkably fierce, and it is the strongest I have felt on any headphone. When I first tried these on, I could not wear them for more than thirty minutes as they put serious pressure on my jaw and temples and they left my head feeling really sore. This did ease up after a while, but those first listening sessions were sincerely painful as a result of the clamp. The headband, I think, features a very poor design as it relies on a single cushion at the center which concentrates the weight and creates a pressure point on my head. I think the RAD-0 would have benefited greatly from going with a suspension-style headband design, or at least a larger surface area with which to distribute the weight. The RAD-0, unfortunately, is not one of those headphones that I can say disappear when wearing them, but they do get a bit better after a while and I have more recently been able to wear them in day-long listening sessions. 

Sound

I really did not know anything about the RAD-0 prior to receiving this review unit, so I did not have any expectations when I first put them on. What I can say now that I have listened to them, however, is that the RAD-0’s tonality has seriously impressed me, as out-of-the-box it is the headphone that for my taste and preferences has been the most enjoyable to listen to. What the RAD-0 offers is, in brief, a tonality that I personally consider to be very “welcoming,” but also very natural-sounding; it has well-defined bass, a little bit of warmth, rich mids with a lush yet realistic presence, and very pleasant treble range.

I do not want to give too much away in this introduction to the sound section, and there are other factors to consider outside of tonality alone for the headphone’s overall experience, so without further ado, let’s see how the RAD-0 performs…

Bass

The RAD-0 has fantastic bass, and it reminds me a lot of the bass on full-size LCD-series headphones I have listened to. For extension, the RAD-0 performs great as, to me, it seems to reach all the way down to 20hz and it delivers that deep, sub-bass rumble. The bass here also has a nice level of presence that I personally think is both enjoyable and adequate, as it sounds to me like its bass shelf under 100hz sits 1dB-2dB lower than that suggested by the 2018 Harman Target Curve. Additionally, it sounded as though the RAD-0 had a slight touch of warmth between 150hz-200hz, but it was very subtle and did not sound like it upset the balance in the bass region. The bass on the RAD-0 is also very well-defined and detailed; sounding even a little more articulate to me than the LCD-2 and Focal Clear. Overall, I would describe the RAD-0’s bass as having a very full, highly-enjoyable sound to it that does not sacrifice any of its control or articulation.

Mids

The midrange is, undoubtedly, my favorite part of the RAD-0’s frequency response. The RAD-0’s midrange has what is, to me, one of the most realistic and enjoyable tunings I have heard from a headphone. The lower midrange is presented beautifully, with a great tonal richness that makes instruments, and specially vocals, sound powerful and full-bodied. I also find the upper midrange to be just as delightful to listen to. The region between 2K-5K has what I find to be just the right amount of energy, and it gives pianos, electric guitars, brass instruments and vocals a very realistic presence that never came across as forward or “shouty” to me. Resolution is a very impressive element in the RAD-0’s midrange, as they present a remarkably clear and transparent image of the mids. In this regard, I personally find them to easily be on par with the HEDDPhone, the HD 800S and they eclipse the performance offered by headphones like the Focal Clear and Audeze’s LCD-2.

It is unusual for me to not comment much on the midrange, as I always find myself thinking “Oh, it sounds a little thin here” or “maybe it’s a little too forward for me.” However, that was not the case at all for me with the RAD-0. Sincerely, I think that this is–for my sound tastes and preferences–the most enjoyable and realistic midrange tonality and timbre that I have heard from a headphone in its stock configuration thus far. 

Highs

I would describe the treble range on the RAD-0 as having a warmt tilt to it, but it has a very good tuning that is able to surface all the tonal nuances in the highs without ever coming across as piercing, strident, or fatiguing. Overtones in this region, to me, seem to be incredibly well-balanced in relation to the mids, which gives elements in the mix very natural and well-textured harmonics. The treble on the RAD-0 also has very good extension, with very nice air qualities above 10K that add a very subtle and sweet glisten in the highs. I really struggle finding a flaw in the RAD-0’s treble range, as it has no strange deviations that make for an unpleasant listening experience. If I were to nitpick, I did think that every now and then 6K-6.5K could come across as ever-so-slightly forward by 1dB-2dB which could introduce a very subtle glare in the low treble, but it was honestly very difficult to notice. Noteworthy, again, is the RAD-0’s resolution in this region of the frequency response. They display the highs with a pristine level of clarity that allows cymbal crashes and splashes in particular to come across immaculately.

Soundstage, Imaging, and Layering

Unfortunately, the RAD-0’s performance for soundstage, imaging, and layering is not quite as impressive as its tonal performance and resolution. Whilst I find the imaging to have a very good sense of positioning, directionality, and depth, the soundstage is very forward and is akin to the more intimate presentation provided by something like an HD 600-series headphones. In terms of soundstage width, it feels narrower than the full-size Audeze LCD-series headphones I have tried, much narrower than something like the HEDDPhone, and even less spacious than the Focal Clear. I think that this more confined-feeling soundscape is emphasized by the instrument separation and distinction not being as being quite as impressive as I expected it to be. Whilst the RAD-0 does do a good job at separating the different elements that compose complex musical passages, and no one track feels like it gets lost in the mix, I was surprised to find that it did not do so as well as headphones like the Clear or HEDDPhone; which I find kind of strange, as I tend to associate planar-magnetic headphones with having better image distinction and instrument separation.

Dynamics

From my experience with them, I would say that the RAD-0 has very good dynamics. I do not think that they have quite as much slam as the Clear or LCD-2, but they still deliver a very satisfying physical sense of impact in the low notes. Percussive instruments, especially kick-drums deliver a very solid low-end punch; whilst Instruments like pianos, guitars, snares and xylophones are reproduced with a very nice strike and attack in their upper registers that add a feeling of weight and tension behind the way they are played. Again, whilst the RAD-0 does not have the absolute strongest sense of punch and slam, I still think that they perform great and make for a very engaging, highly-enjoyable listen.

EQ

The Rosson Audio Design RAD-0 is the first headphone that I have listened to and have seriously pondered on whether or not I wanted to use EQ at all, or if they needed it. As per usual, however, I did end up using EQ just to bring it even closer to my personal preference. The biggest change I make is that I reduce some of the 200hz warmth in the bass. I also adjust 6.5K to make sure that there is no chance that it will come across forward in any tracks. This is my EQ profile for the Rosson Audio Design RAD-0:

  • Peak at 200hz, -2dB Q of 0.7
  • Peak at 6500hz, -2dB Q of 4

Conclusion

Given its Audeze heritage, it is unsurprising that the RAD-0’s sonic characteristics and presentation are very reminiscent of that of full-size LCD-series headphones. However, the RAD-0 is not challenged by the usual issues that throw off LCD headphones’ tonal balance, and it instead delivers a slightly warm, tonally rich, and natural sound that I think many will enjoy. Admittedly the RAD-0 was, at least for me, held back a bit by comfort issues. However, if the comfort on this headphone is not a problem for you, or if Rosson Audio Design comes up with some sort of headband revision that improves weight distribution and clamp, I think that the RAD-0 is a fantastic headphone that I can gladly recommend. I truly believe that when you combine its superb tonality, technical performance, and artisan design, the RAD-0 is amongst the best planar-magnetic headphones currently available in the market.

… I guess you could say it’s a pretty “rad” headphone…

-Chrono

Watch the video review here:

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