The RAAL-requisite SR1a is an incredible innovation in headphone technology. The core design is more like a pair of nearfield studio speakers strapped to your head than traditional headphones, and it uses a ribbon speaker design for its drivers, providing an incredibly realistic reproduction of the original recording. To complement the SR1a, RAAL released the HSA-1b amp, which we tested along the SR1a for this review.
The Build and Design
When I talk about multi-kilobuck headphones, most people either imagine some kind of wireless, noise-cancelling, gold plated monstrosity, or if they’re more creative, something not too different from the SR1a, with its totally unique sci-fi look. Despite its angular, metallic look, the SR1a is reasonably comfortable, and it uses a double strap design to provide multiple angles of support on your head. Even with that design it doesn’t always feel particularly secure, and I wouldn’t recommend moving around too much while listening to it.
The earcups aren’t so much cups as they are blades, and unlike traditional headphones which cover your ears or rest on them, the SR1a is essentially a headband with ribbon speakers on an adjustable pivot which allows you to control the angle of the sound. You can close them in to provide a bit more impact or open them up to have a wider more open soundstage.
The catch here is that the SR1a requires a 100W speaker amp to drive, and will generally need the speaker interface box as well (unless you’re using the Schiit Jotunheim R or RAAL-requisite HSA-1b as your amp).
The packaging for the SR1a is pretty impressive. Inside of the shipping box, there’s a large tough-looking travel case which contains the headphones, cable, and the speaker interface box (if you opted for it). The included cable is a female 4-pin XLR which will only work with the speaker interface box, and the aforementioned collection of amps purpose designed for the SR1a.
Also of note is the fact that there is absolutely nothing even remotely resembling sound isolation on these. They’re literally just open speakers attached to your head. Everyone in the room, and probably the next room, is going to hear what you’re listening to, and you’re going to hear them too unless you crank it up.
The SR1a just sounds “right.” When you plug it in, and listen to a song you’ve heard 100 times on 100 different headphones and speakers, the SR1a gives you the distinct feeling that what you’re hearing right now is finally it. Now you’ve really heard it the way it was meant to be heard.
The tuning is very neutral and generally linear through the bass. The soundstage is massive – more like listening on a wall of speakers than headphones – and the imaging is vivid and precise. The response is fast and dynamic, and the detail retrieval world class. The bass and physical impact are perhaps the only aspect of the headphone that I’m not overwhelmingly enthusiastic about. With the standard speaker interface box, I found the impact to be slightly lacking, but with the RAAL-requisite HSA-1b, the low end impact fills out nicely.
Have you ever heard one of the stories where someone says that when they were a kid, they thought that every time they heard a song on the radio or played a tape it was being performed live at that very moment so that they could listen to it? Like, Michael Jackson had to get up at 12AM and sing “Beat It” for you because you were playing his tape at that moment? That’s what the SR1a feels like. When you put all of the characteristics of the SR1a together, it doesn’t just look like something out of a science fiction movie, it feels like an actual science fiction portal through time and space to the studio space where the song was originally recorded.
On The Bad Plus’s avant-jazz take on U2’s “Staring at the Sun,” the SR1a delivers the opening piano lines with an intimate softness. The bass feels almost impossibly realistic, like it’s just a few feet away on the stage, not being projected through your ears. Drums are similarly powerful. The SR1a’s soundstage presents this three piece band as sounding almost impossibly huge, while retaining the feeling of an intimate private concert.
The SR1a deftly arranges and presents the complex layers of guitar, bass, keyboards, and drums created by Dream Theater on their “A Mind Beside Itself” song suite. Through the most complex heavily layered sections, the SR1a enables you to pick out every note of each member of the band. You can easily shift your focus to the instrument currently highlighted in the mix, or to one of the background layers. The vocals are crisp and clear. The instrumental timber is incredibly lifelike. Electric guitars and synths sound massive and powerful, and when the acoustic instruments hit, they’re clear and natural. Through every shift in dynamics – from the progressive metal tour-de-force instrumental “Erotomania” to the acoustic ballad “The Silent Man” – the SR1a remains focused and coherent, delivering an experience that is both analytical and emotional.
Outkast’s “Ms. Jackson” demonstrates the versatility of the SR1a as it provides solid bass response and low end impact. The sung vocals are smooth, and on the rapped verses, Big Boi is right in your face. The ambient samples and synths on the track create a wide soundstage and completely surround the listener. The slap bass hits with a touch of impact and a full load of detail and texture.
Listening to Christoph Koncz’s performance of Mozart’s “Violin Concerto No. 4 in D Major” demonstrated the SR1a’s capabilities in presenting a wide and deep soundstage with holographic imaging. It provided a vivid sonic picture of the string ensemble, while also providing broad dynamics, capturing the softness of pianissimo sections and the energy of fortissimo. The lead violin is presented bright and sweet, and never harsh or sharp.
The HSA-1b is a headphone and speaker amp (Headphone Speaker Amp is literally what HSA stands for) which provides loads of power to drive even the most demanding over-ear headphones, and the versatility to work with speakers as well. The design could very well make it the center of a multifaceted hi-fi setup that runs your headphones and speakers with the ability to easily switch between multiple sources. Of course, what's more important for our purposes today, is that it was also designed to be a perfect pair with the SR1a .
It features XLR and RCA inputs, and outputs for standard 4-pin balanced XLR, 6.3mm unbalanced, speakers, and the reversed 4-pin XLR for the SR1a. There are a series of switches on the front which allow you to switch between RCA or XLR input, speaker or headphone output, and between standard headphones and the SR1a. The volume control is a big red wheel with a nice tactile click between each step of the volume, which is very satisfying to use.
I had previously spent some time with the SR1a using the speaker amp interface box, Schiit Vidar speaker amp, and Hugo 2 as the DAC. For this review, my signal chain was the RAAL-requisite HSA-1b with the Hugo 2. Altogether the combination of the SR1a, HSA-1b, and Hugo 2 proved to be a beautiful and transcendent listening experience.
I had a couple takeaways from my time listening with the SR1a and HSA-1b. The first takeaway is that the HSA-1b perfectly complements the open, transparent sound of the SR1a. If you love the SR1a, but simply want more of the incredible soundstage and vivid imaging, and more of the neutral, realistic delivery, the HSA-1b gives you just that.
The second takeaway I have for the HSA-1b is that as a pairing with the SR1a, it supported and enhanced the low end to a degree that it no longer felt like a weak point of the SR1a. Where previous listening had left me feeling that the SR1a was an amazing headphone with a little bit less bass and impact than I’d like, the HSA-1b fills in that gap to complete the SR1a’s sound.
The Bottom Line
The RAAL-requisite SR1a is like nothing else out there. Its looks are one-of-a-kind, and the sound is unlike any other headphone you’ve heard before. The HSA-1b takes it to the next level providing reinforcement of it’s massive, powerful sound. Put them together and you get a listening experience that’s half loudspeaker, half portal through time and space, and fully amazing.