Review | RAAL-requisite SR1a Earfield Headphone Monitor

The RAAL-requisite SR1a headphones are unequivocally the most sensational audio product I've ever heard. Honestly, no product has ever captured my attention, caused me to listen to more music, or garnered my enthusiasm like the SR1a Earfield headphone monitors.  I've listened to them nearly every day since I took delivery on Thursday February 13, 2020. I frequently sit across the room from a $100,000+ audio system, looking at it, while listening through these headphones. The SR1a is that good. Stunning, amazing, and the only headphone capable of pulling me away from my main audio system. 

That's quite a lofty paragraph. But, the SR1a is a lofty product deserved of all the accolades. These headphones literally change the game. 

Headphone Guys, Stax, and My Predisposition

I'm going to backup just a bit to provide some context. 

I was never a "headphone guy" in the same sense that many of my friends are headphone guys. I've always had three or four pairs of headphones and a headphone amp or two for mostly casual and some serious listening. My friends, on the other hand, know most headphones inside and out and have three or four pairs of flagship headphones and flagship level amplifiers. Thus, when it came time to replace my Sennheiser HD600 cans, I had to do some serious research.  

Yes, I was still using HD600 headphones as my personal flagship (is personal flagship like alternative facts?) until early 2020. Partly ashamed, yes, but also a subscriber to the motto, use it up, wear it out, make do, or do without. The HD600 headphones are still solid to this day, and I didn't want to replace them until the perfect opportunity arose, enabling me to give them away and feel really good about it. This opportunity provided the perfect reason to obtain a new reference level pair of headphones. 

I immediately started looking at the Stax double-aught series. I'd always wanted a pair of Stax SR-007, then SR-007 MK2, then SR-009, and recently the SR-009S. There's something about the sound of Stax electrostatic headphones that had always sucked me in, seduced me, and made me consider spending well over $10,000 (headphones and amplification). Stax is like Leica in that the products are very high quality, they both have a lust factor that consumers can't resist, and both can be objectively bested for less money. But objectivity isn't the point of Stax or Leica. Anyway, I sent a few emails to people asking for opinions about the SR-009S. Then a press release hit my inbox from Schiit Audio. It announced the new JOTUNHEIM R headphone amp that was built specifically for RAAL-requisite true ribbon Earfield headphone monitors. 

Dead set on Stax at the time, I sent an email to Jason at Schiit, not to get a review sample of the JOTUNHEIM R, but to ask if Schiit had plans to build an amp for Stax headphones. I was still in Stax mode at the time, and thought a Schiit electrostatic headphone amp would make the purchase of a Stax based system much easier on my pocketbook. Jason's reply piqued my curiosity. Short and to the point, Jason said, "Nope, I'm a bit scared of high voltages." Jason followed a few minutes later with, "Not to sound like a shill, but have you heard the Raals? That's another reason we won't be bothering with stat amps."

Jason and I exchanged a few more emails, then I went on a RAAL-requisite research binge. Too bad I hadn't done this when our own JoshM asked me to obtain a review sample of the SR1a over a month earlier. Nonetheless, I ordered a pair of the headphones a few hours later. Sight unseen and sound unheard, I took Jason's word that these were special. The other factor that helped push me over the tipping point was the all-in cost of the SR1a was less than the cost of just the Stax headphones. 

Credit Jason at Schiit for changing my audio world, with honorable mention going to JoshM for what should've changed my audio world.

Given that I wasn't a headphone guy, I thought the SR1a headphones would arrive, I'd listen for a day or so, then they'd sit on the shelf until I needed them as a tool for my work. Once in a while a set of revealing cans can illuminate good or bad aspects of a component's design. Having revealing headphones on hand can help me cut to the chase while evaluating a product. Good cans are like a doctor's stethoscope at times. 

I thought things would progress this way because a couple years ago a dealer sent me a SR-007 MK2 based system, just to use for a bit. The fate of this Stax system was as I described above. The sound was fabulous, but the headphones sat on the shelf 95% of the time. Back then, I also looked at headphones as a compromise for those who didn't have the room, environment, or significant other sign-off for a full blown speaker based audio system. The odds were really in favor of the SR1a making it to the big leagues for a cup of coffee, then being sent to the minors or sitting on the bench for the remainder of their audio career in my house. 

Upon arrival, the SR1a headphones entered the race for my audio attention with shackled legs and one arm tied behind their back. I was predisposed not to like them nearly as much as my main system and I had no need to use them because I sit next to my main system all day, every day. I soon discovered that the SR1a would change my listening habits substantially. 

They're Here (to be read like Heather O'Rourke in Poltergeist, circa 1982)

The RAAL-requisite SR1a headphones arrived in a pelican-style hard case that could, no doubt, withstand shipping by even the most careless of UPS personnel. I immediately unboxed them and got to "work." 

The SR1a headphones are unlike anything else on the market that I know of, not only for their sound, but also for how they're powered. They require one of two amplification methods. Either a traditional speaker power amplifier connected to the ribbon / amp interface box, or a purpose built amp designed for RAAL-requisite headphones. Currently I know of two amps that fit this bill, the RAAL-requisite HSA-1a ($3,900) and the Schiit Audio JOTUNHEIM R ($799+). As I write this review, Schiit is sending a JOTUNHEIM R for evaluation. I plan to write a full review of that amp on its own and won't include any further comments about it in this review. 

The ribbon / amp interface box connects between a speaker amp and the SR1a, to achieve 5.6 ohms of combined resistance and 140W of power dissipation with a moderate temperature increase. The SR1a ships with a pair of very short speaker cables the user can run from his/her amp to the box. Think of the interface box as a pair of speakers. Connecting it to one's amp with speaker cables is pretty straight forward and should neither be overthought nor overcomplicated by those trying to figure these headphones out. The audio signal traverses this interface box, coming out the front 4 pin XLR connector, into the SR1a headphone cable and on to the Earfield monitors. 

RAAL-requisite recommends powering the SR1a headphones with roughly a 100 watt, into 8 Ohms, amplifier. There's no getting around the fact that these headphones require good power, but experimenting with amps at, over, and under this guideline is highly recommended. To date I've used the SR1a with a McIntosh MC275 (MK V), Audio Research VT80 SE, and a pair of Schiit Audio Vidar monoblocks. While developing the SR1a, the team at RAAL-requisite used the Benchmark AHB2 power amplifiers extensively and highly recommends them to this day. 

There are many really interesting details about the SR1a headphones such as user replaceable drivers, its 0.2 Ohm load, and the fact that it's the world's first true ribbon headphone, but these facts quickly fade from memory compared to the incredible listening experiences I've had. The technical details can also be read on RAAL-requisite's site or Googled easily. For this reason, I'm going to eschew further parts descriptions and specification recitation in favor of telling my own story about these incredible headphones. 

Mix, Match, and Enjoy

I've been listening to the RAAL-requite SR1a headphones for roughly 2.5 months, with three different amplifiers, and many different DACs and servers. I've yet to hear a direct drive headphone amplifier that bypasses the ribbon / amp interface box, but the very fact that this interface box is otherwise required has made experimenting with different amps incredibly fun. As a two channel big system guy, I have spare amps laying around and a better familiarity with traditional power amps than I do headphone amps. Thus, grabbing my MC275 and connecting it to my headphones has tremendous appeal, as does looking at the huge world of amplifier possibilities that opens up when using the interface box. 

Some day I will connect my Constellation Audio Inspiration series monoblocks to the SR1a headphones, just because I can. A system like that is a bit absurd, not because of price, but because of the sheer size. I also have a couple very interesting integrated amps on the line for review and I can't wait to connect them to the SR1a headphones. It's quite freeing to think about all the possibilities one has for powering the SR1a. 

Enjoy More

I started listening to the SR1a in a system consisting of a Sonore Signature Rendu SE optical, Berkeley Audio Design Alpha USB / Alpha DAC RS3, and a pair of Schiit Audio Vidar monoblocks connected to the ribbon / amp interface box. I was immediately convinced that these headphones were in a league of their own. In my first comments in the Audiophile Style forum I said, "The speed and detail of these headphones is really something to behold. The bass is better than I expected as well. Perhaps too much reading into specs and opinions about how low a headphone must go with respect to frequency response." But, rather than recap my existing comments, it's time to share more about my experience with the best headphones I've ever heard. 

Readers looking for a flagship versus flagship headphone comparison won't be served well by this review. I prefer to describe what I hear and compare the sound through the SR1a headphones to that of traditional stereo systems with large floor standing speakers. That's the world I live in everyday and it's also why I know these headphones are so special. If a guy like me can sit in his listening chair and split his time 50/50 between the SR1a and Wilson Audio Alexia Series 2 loudspeakers, something is good afoot. These headphones have seriously pulled me away from my main system so much that lately I've split my listening time equally between speakers and headphones.

Listening through the SR1a headphones for literally hours on end to any music in my collection was pure bliss. I suffered zero fatigue both sonically and physically. I usually get tired of on-ear, in-ear, and over the ear headphones after an hour or two, no matter how comfortable the design. The SR1a is in another league with respect to comfort because it doesn't rest on or around one's ears. When I wear them I feel the top strap on my head and a slight pressure from the vertical cushions that rest against the side of one's head. Compared to wearing "normal" headphones, wearing the SR1a is like wearing air.

Over The Top

Over the years I've been fortunate enough to hear a couple audio systems that were so dialed in I could listen to any type of music and not only enjoy it, but be blown away. I'd never heard some of my favorites in the same was as I heard them through these systems. The RAAL-requisite SR1a is 100% in this category. I can listen to absolutely any music and be enthralled. Don't kid yourself though, due to the laws of physics I can't connect a 1000W amp and play Dr. Dre's The Chronic at 120 dB without some problems. What I'm talking about is playing everything from Black Sabbath to Bruce Springsteen to Miles Davis to Dua Lipa to the Minnesota Orchestra and everything in between. All of it sounds spectacular through the SR1a. 

I'm literally trying to write this review and struggling because I'm listening to Deep Purple's Machine Head and it has never sounded better. I've never heard more detail on this album than what I'm hearing right now. I've also never liked the album more than right now. The SR1a has given me new respect for many albums that I'd always tossed aside. For example, the other night I got on an Eric Clapton kick and listened to most of his old catalog. I'd never done that in my 44 years on this planet. I now have a new respect for Clapton's music. This would never have happened without the SR1a headphones. 

One aspect of the SR1a that I couldn't have imagined would play out like it has, is the fact that listening through these headphones is absolutely addictive. I have an addiction to listening to music through them like no other component or system in my life. Before they arrived I'd never listened to artists' full catalogs or explored deep cuts and albums from many artists, like I've done recently because of the SR1a headphones. Isn't this what it's all about for many of us?

System Synergy

I spent a decent amount of time listening through the SR1a headphones connected to a pair of Schiit Vidar monoblocks before trying other amplifiers. I wanted to get a handle on the sound while using amps that I knew worked well with these headphones. The Vidars powered the SR1a very well, enabling them to display dynamics like I'd never heard from a pair of cans or speakers. I'd have no problem living with Vidars and the SR1a and I recommend the combination very highly. For the price, the Vidars are tough to beat. 

Once I had a sonic baseline I moved on to my freshly re-tubed McIntosh MC275 MKV. I'm glad I tried this combination, but it failed to deliver any magic. Sonically the MC275 ran out of gas before it could deliver any punch, detail, or delicacy. This shouldn't be looked at as a fault on the part of the amp, rather it's just a mismatch that actually shouldn't work. According to RAAL-requisite, a 100W into 8 Ohm amp and even a 150W amp for classical and Jazz is highly recommended. The MC275 was built for a different purpose. 

After setting aside the MC275 I picked up an Audio Research VT80 SE stereo amp from the company's new headquarters, roughly 10 minutes from my house. According to ARC the VT80 SE features, "75 watts per channel continuous from 20Hz to 20kHz. 1kHz total harmonic distortion typically 1% at 75 watts, below 0.05% at 1 watt. (Note that actual power output is dependent upon both line voltage and ‘condition’ i. e.: if power line has high distortion, maximum power will be affected adversely, although from a listening standpoint this is not very critical.)" Given ARC's comment on line voltage and condition, I'd be remiss if I didn't mention that my entire system has been connected to isolation transformers from a tiny Northern California company named 512 Engineering. The impact of these transformers in my system has been incredibly revealing and shouldn't be overlooked for almost any other system.  

Even though the wattage of the MC275 and the VT80 SE are identical, the sonic results couldn't have been more different. The sound through the VT80 SE was nothing short of glorious, detailed and delicate, with plenty of punch. Connected to the ARC stereo amp I gravitated toward both the dCS Rossini DAC and newly released APL HiFi DSD-SR MK2 DAC. When the Rossini DAC was in place I controlled volume with its built-in attenuator. Conversely, when I used the DSD-SR MK2, I changed things up quite a bit. I used HQPlayer to convert all audio to DSD256 and I used HQP's digital volume control. This HQP > APL > ARC > SR1a combination delivered amazing sonic results. Unless otherwise specified, the following sonic impressions were all delivered by this magical combo. 

How many times can a guy listen to the band Tesla play old hits from the 80s and 90s on a new release titled Five Man London Jam? According to Roon, the answer is thirteen. There's just no way I would listen to this album thirteen times, in the span of a couple weeks, without the SR1a headphones. Through my main system I'd probably put this new album on a couple times, relish in the memories of my freshman year in high school, then move on to something new from ECM on Qobuz. The SR1a reproduced this album so well, that I kept playing it over and over. These headphones have made me believe there is magic in every recording. It just has to be extracted using the right tools / components. 

I've been on a little Chris Isaak kick of late, enjoying his albums Forever Blue (1995) and Baja Sessions (1996). Listening to Baja Sessions, the ARC VT80 SE delivered an ever so slight bit of tube allure that pushed my enjoyment of the SR1a headphones to a stratospheric level. Isaak's cover Roy Orbison's Only the Lonely sounded so beautiful I could've listened on repeat until the tubes had burnt out. Chris Isaak's voice had an amazing gloss and realism that I'd not heard through any other system, headphones or speakers. The naturalness of his acoustic guitar is also otherworldly for a pop recording. Near the end of the track (2:15 - 2:35) Isaak brings his voice from its upper frequency limit down to its lowest depths, as he transitions from one verse to the next. The detail that can be heard through the SR1a headphones is absolutely impressive. Hearing Chris Isaak in this way, with such incredible detail, is an experience that's both enjoyable and makes me want to listen to more and more music from him and other artists.

One aspect of the RAAL-requisite SR1a that deserves discussion is this headphone's ability to reproduce dynamics. I've never heard a headphone like it and have only heard a handful of very large speaker based systems that are capable of reproducing dynamics at this level. On one hand, the listener must be careful not to damage his/her hearing. Dynamics this great can really creep up on the listener and before you know it, your ears hurt. On the other hand, dynamic transient attacks are hallmarks of live music and should be cherished by those seeking reproduction as close as possible to the real thing.

Case in point, Three Blind Mice album TBM-17, Live! by the Terumasa Hino Quintet. The opening track, Stella By Starlight has a dynamic range (R128) score of 21.1 LU. This track, played through these headphones, can tear one's head off. I've nearly had it done to me several times. I love this track. The sound of Hino's trumpet goes from soft and smooth to brash and boisterous in an instant. It's 100% delightful as long as one understands what's coming and has the volume positioned accordingly. The SR1a delivers the goods on everything from the softest notes to the overbearing blowing when Hino really gets going. Elevating the SR1a, and delivering all the power required, was the ARC VT80 SE. This 75 watt amp delivered like it had plenty of headroom to spare. At the same time, the VT80 SE never lost a hint detail, delicacy, or its glorious sonic signature. 

If you want tone, you got it. Throw on Mark Knopfler's One Take Radio Sessions and place the SR1a on your head. This live in studio EP, with tracks off the Shangri-La album, is jammed full of beautiful tone from Mark's Gibson Les Paul Standard 58. I'm not even a guitar freak, like some of my friends, but I get lost in this recording when played through the SR1a. These headphones make it sound like I'm on my hands and knees with my ear placed directly in front of Knopfler's Fender Tweed Deluxe amp. I can easily see why RAAL-requisite has a long list of studio professionals using the SR1a. They're absolutely incredible. 

Listening to the audiophile classics Let Me Ride and Nothin' But A "G" Thang from Dr. Dre's The Chronic (released to streaming services mysteriously close to 4/20/2020), certainly isn't like sitting on top of a JL Audio Fathom subwoofer, but it provides a unique experience nonetheless. Through the SR1a one can hear the surprising number of ancillary sounds and sub-textures that usually get lost underneath the boom of the main groove. Listening to The Chronic on these headphones is a different sensory experience in that one can hear what's actually on the recording, and some pretty good backing vocalists such as the late G-Funk man Nate Dogg, Warren G, and the little known Ruben Cruz and Jewell. 

Sliding over to an adjacent genre that's just as exciting, I must cover a little classical music in this review of the SR1a headphones. I'm no classical aficionado but I have some favorites that I listen to frequently. One of these is Reference Recordings' Bolero! Orchestral Fireworks recorded at Orchestra Hall here in Minneapolis in 1999. Track 1, Colas Breugnon, composed by Dmitry Kabalevsky, opens with a bang. This opening is followed by a great mix of percussionists delicately tapping triangles, loud horns, soft flutes, and a memorable and meandering string section. This track has it all. Great music, great musicians, and great sonics. Through the SR1a, this and the remaining tracks sound stunning. I don't believe it's possible to hear more detail on this recording than what's on display through these headphones. This incredible detail shouldn't be mistaken for brightness, harshness, or the often dreaded clinical sound. The SR1a isn't like that. It really delivers what's on the recording and what's coming through the upstream electronics. 

I didn't detect the SR1a falling apart in any way, even during the most demanding classical passages. For example, on the Kansas City Symphony's Britten (out of print and unstreamable), track 6, Passacaglia, everything from micro details to jarring percussion is all on display. At about 5 minutes into the track the action starts to build up before crashing down roughly one minute later. At its height, the entire symphony is figuratively banging on, blowing into, or drawing bows through, everything within arm's reach. Yet, the fine details and instrument separation are all there. Everything remains cohesive even under pressure. 

I know I could go on and on, but I can't make my points any clearer. These are the best headphones I've ever heard and I have strong doubts there is anything better on the market today. My single complaint about the SR1a is that its design precludes one from listening while laying down. It just doesn't work. I tried reversing the strap that can optionally be warn behind one's head, by running it across my forehead. I tried positioning the headphones a bit differently than normal, but nothing worked. I just can't listen to the SR1a while laying down. I accept that, but not willingly. 

Conclusion

Well, that was either the most superlative laden, over the top, word salad of a review you've ever read or you're currently adding the SR1a to your online shopping cart. I understand if some readers think I was a bit too liberal in handing out accolades to the SR1a, but I have no problem standing behind every one of them. The RAAL-requisite SR1a is truly a game changer. There's no headphone like it available today, with respect to both design and sound quality. 

The SR1a is the only headphone to ever pull me away from my main two channel speaker based system. This doesn't mean I'm converting from my Wilson / Constellation system to headphones, because nothing could be further from the truth. There are many things headphones just can't do. There's no Johnny Cochran to get one around the laws of physics. However, the amount of time I now spend listening to my main system is substantially reduced because these headphones are so good. 

All music lovers, audiophiles, and even gear junkies need these headphones as part of their audio arsenal. It's just that simple. The RAAL-requisite SR1a are unequivocally the best headphones and the most notable audio product I've ever heard. Period. End of story. CASH Listed.
 

All images shot with Hasselblad 503CW, Zeiss / Hasselblad 50mm CFi lens, Fujichrome Velvia 100 film or Ilford FP4 Plus B&W film.

Community Star Ratings and Reviews

I encourage those who have experience with the RAAL-requisite SR1a to leave a star rating and quick review on our new Polestar platform.

Product Information:

• RAAL-Requisite Earfield Headphone Monitors ($3,499)
• SR1a Product Page
• RAAL-requisite SR1a Preliminary Owner's Manual (22.6 MB PDF)
• RAAL-requisite SR1a Cutsheet (6.7 MB PDF)

Associated Music:

• Audiophile Style 50 (Qobuz)
• Computer Audiophile PJ4CA Playlist (Tidal)

Associated Equipment: