Country of Origin
Reviewer: Srajan Ebaen
Financial interests: click here
Sources: Soundaware A280 as SD card transport, Kinki Studio Vision DAC-1
Preamplifier: Nagra Classic, COS Engineering D1, Vinnie Rossi LIO (AVT module)
Power & integrated amplifiers: Pass Labs XA30.8; Goldmund/Job 225; Nord Acoustics NC500 monos; LinnenberG Audio Liszt monos; Crayon Audio CFA-1.2; SAG AIO, Kinki Studio EX-M1
Cables: Complete Crystal Cable loom including interface jumpers
Power delivery: Puritan Audio Labs PS106-DC
R³: Raal Requisite Redux. Plenty of pixels I've spilled on the SR1a earspeakers already. Here are some more. Splash.
By its very ribbon nature, this headphone would present as a near dead short to any amplifier. Hence its included purely passive amp/ribbon interface box. It not only compensates for the inherently rising response of a line-source in such extreme proximity. It inserts resistance to raise the load impedance to 6Ω. Voilà, happy times for any transistor amp of a recommended 100/200wpc into 8/4Ω. Most that power burns off resistively. The ribbon doesn't need it. But the current it does need particularly for LF transients down to the 30Hz it can reproduce will pass. Now the question becomes, what amplifier to pick?
By virtue of their AKG K1000-ish floating baffles plus being true ribbons of very low resonant frequency and no magnets between membrane and ear, there's blinding speed from lack of energy storage expressed as a super-clean impulse response; and extreme dynamic tracking. It makes the SR1a unusually transparent to preceding ancillaries. As their quality elevates, so does the sound at your ears. The SR1a inserts far less intermediate buffering than most transducers. Because of it, there's an easily generated misconception that's already spread on the forums. The SR1a need extreme hence expensive amplification. Poppycock. As with loudspeakers, one can shop smartly to get higher return on investment. A Schiit Vidar or two spring to mind.
On our SR1a, I've tried the April Music 50wpc Stello S100MkII, the SAG AIO, the Pass Labs XA-30.8, the Nord Acoustics Ncore 500 monos with Rev D buffers, the Crayon CFA-1.2, the LinnenberG Liszt monos and Goldmund's Job 225. All of them worked just fine. Dedicating a hulking €6'500 class A amp to headfi duties simply felt unreasonable. Probably because the interface box obliterates an amp's own damping factor, even the Hypex amps with their extreme damping—and especially when preceded by our Nagra Classic tube preamp—were brilliant. But to shanghai a €15'000 Nagra to headfi duty felt excessive again. As such I ended up with our COS Engineering D1 D/A converter with premium analog volume driving the hi-gain $1'495 Job 225. €9'000 for the DAC/pre still felt unduly stiff relative to a €3'500 earspeaker. But not needing it elsewhere, I lived with it until…
To gild the lily because I had them, I replaced the stock interface jumpers with Crystal Cable silver/gold sorts. It made a nice little difference but is far from required and of low ROI.
… I awoke one fine morning with a surprise idea (those do happen, occasionally and often late). Really, the ideal thing here would be a simple high-power integrated amp from a proven high-value brand. Wasn't my wife listening to just such a one in her studio? And didn't I have Simon Lee's All-In-One to replace it with should she agree to part with her <€2'000 Kinki Studio EX-M1? Losing her CD transport, DAC and integrated for a single box was a great benefit to Ivette so she happily agreed. Out went her EX-M1 and matching ~€1'250 Vision DAC-1 to hoof it upstairs. Source remained my usual Soundaware A280 as just SD card transport. This became a perfect driver for the SR1a, delivering a high-class 215/400wpc into 8/4Ω with 256 x ¼dB step precision attenuation to dial in desired SPL in ridiculously fine increments.
And there today's redux ends before we get reflux from too rich a ribbon diet. From everything in our hardware library, the Kinki Studio EX-M1 is the ideal SR1a driver. It just took remembering that Ivette had one in her room then abscond with it. Sonically it's a clear step up from the Job 225 and for little extra money includes a proper linestage with balanced input. Add a DAC that matches it on value like its stable mate, a Jay's Audio DAC-2 SE or smaller Denafrips and you're home. If you're a deep pocket, pursue a CH Precision amp or equivalent and be happy with your über headfi rig. Just don't tell people it's required and that something far more affordable wouldn't properly do the job. Because now you'd be talking hot air out of dual front ports. It's simply not true.
If Goldmund's JOB INT is still available, that'd make for a great candidate with DAC. So if you've got an SR1a in your sights, think of a modern super integrated at your budget. As long as you stick to the recommended 100-watt rating, you'll be just fine. Don't listen to the extremists. Expensive amps aren't a requirement at all. All you need is sufficient power…
Postscript: Since I reviewed the SR1a, I also had a chance to review MrSpeakers' €3'000 Voce electrostat on an EL84 OTL Blue Hawaii SE by HeadAmp. Now I can also state that the SR1a remains in a different league should you prioritize speed, dynamics and resolution, hence the hyper clarity and directness which result from it. Unless the Abyss which I've not heard exceeds it on that score, that makes the Raal Requisite king of those sonic disciplines.
PPS: A day past publication, Alvin Chee of Vinshine Audio checked in. "Thanks for the coverage of using the EX-M1 with the SR1a. Coincidentally, two customers in Singapore are using the very same setup!" When paying customers enjoy a combination before a reviewer discovers it, it's a lovely confirmation – for the reviewer.