I am really well equipped with great headphones and amps that I love and I don’t need to buy any more - haaa hahahaha, thank you, I’ll be here all week.
Seriously, I use planar magnetics and love the Hifiman Susvara and Audeze LCD-4z. But I became interested in the very unusual RAAL-Requisite SR1a phones, they have been written up in several places since the fall. Lots of glowing commentary, I’ll put some links below. If you want to hear about how they removed veils from the music you have to go there, I don’t do reviews. (Yes, they are perfectly satisfactory.)
But there is some interesting technology. The SR1a are ribbon speakers that hang beside your head, there are no cups, they don’t seal to your head, you can adjust the angle of them. No isolation, of course. It’s like having a pair of micro-Magneplanars hanging there.
However, here is the quirk: you can’t drive them with a regular headphone amp. The problem is that their impedance is 0.2 ohm. Any amp will see that as a dead short, and will either fry or go into protection. RAAL provides an adapter box for a speaker amp of at least 100 W amp which diverts most of the power into heat. But from what I have read, a better solution is an amp dedicated to this kind of load. RAAL offers one, and Schiit has released one, the Jotunheim R, which is what I got.
But note that this is a very unusual amp that works only for the SR1a, you can’t plug in regular phones. We have recently had a discussion here of the Susvara which are very demanding to drive. I saw a note that at a 120 dB peak, they draw 290 mA (6 W into their 60 ohms), which the Benchmark HPA4 and Chord Hugo TT2 can deliver but the portable Hugo 2 and an iPhone cannot. Well, the Jotunheim R can deliver 13,000 mA of current into the SR1a 0.2 ohms. 13 amps! Holy! And the SR1a specs efficiency as 91 dB/W. Ok, 91 dB, that’s normal, ho hum. No, no, that’s 91 dB per watt, not milliwatt. Holy holy!
On the other hand the Jotunheim R delivers only 5 V, so if you dared plug in the Susvara you would get less than 0.5 W. So current strength is not the same as voltage strength, power delivery must be match the impedance of the phones. “How much do you need to turn up the volume control?” The volume control is like the accelerator pedal in a car, it’s how you communicate a wish, but pressing the pedal to the metal has different effects in a Ferrari V12 and a Prius or an eighteen-wheeler. This whole thing is a master-class in Ohm’s Law.
This also leads to complications for setting up different headphones. All these versions with different requirements — SR1a, Susvara, Stax electrostatics, mainstream planars or dynamics, IEMs — increasingly require different amps, some are mutually compatible but not all. And each needs a streaming end point and DAC. Ok, you can plug multiple amps into one DAC but it is often a hassle involving cables on the backs of boxes. And while I like my Chord stack, I don’t want to buy several of those, one for each headphone. I could get cheaper DACs, but getting the greatest headphones and running them off a mid-fi DAC doesn’t make much sense.
Plus there is another problem: some of these headphones need some DSP, the SR1a were originally designed for monitoring during recordings and are aggressively neutral, some consumers may prefer a “house curve”, I don’t know yet, am experimenting but I think I will. And the Audeze have custom convolution filters, and of course speakers often have room correction. This means if you plug these chains into the same streamer, Roon sees them as the same endpoint, and you have to manually switch DSP preset, and switch cables and turn amps on and off. Oh, the horror! Ok, I can live with that, but knowing myself I will forget, using the wrong DSP preset will only impair the sound, plugging the wrong thing in the wrong jack may damage something.
Anyway, lovely so far.
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