HiFiMan Susvara Over-Ear Planar Headphone - Official Thread

Anyone have experience with the Hifiman EF400 powering the Susvara? Haven’t been able to find many reviews on it. In the meantime, waiting for a Cayin iHA-6 to arrive.

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I don’t but if it’s any indication…when I asked about the ef1000 at the Hifiman booth at Canjam to try with Susvara they said they only had the 400. I asked if it could power my Sus and neither of the Hifiman guys recommended it. So I didn’t even bother to get it out to try.

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Measurements&Review of HiFiMan EF400 R2R DAC/HPAmp - L7Audiolab had it tested, it does not measure well (like audibly distinguishable). But it is powerfull.
The lessons learned I can give is: I have the sp400 which is similarly powerfull (around 4 amps at 50ohms (with 4v dac output) , and it drives the susvara well, but if you eq the bass, say, 4db (like I do) you’ll feel that you need the volume at close to max, which is not good for the longevity of the amp itself. I suspect the ef400 being similar in that regard. If you don’t eq, then ignore the second part of my comment.

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The “Hifiman guys” are salesmen (not engineers). If they’re doing their job well, then they’ll wanna recommend their most expensive offering, to get good commissions out of it (And get hired for the next event; 'cause I’ll bet they are seasonal freelancers).


Hey all, realise this is a bit of a spicy first post, but as an owner of the Susvara alongside a A90, which is readily seemingly ridiculed in communities like these and HeadFi, I really just want to see if I’m missing out on much by not going into the hefty speaker amps.
In my city we don’t have all that many options for trying out these varying setups, so it’s typically blind purchases being made. Hence I like to have some actual objective proof of things before spending the big bucks.

So key query, is there actually any ABX style testing done with speaker amps over something lower end like an A90 / whatever other cheaperish headphone amp to prove the claims of bass suddenly being less anemic etc?

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The A90 is a decent amp and does a good job with the Susvara, but you can get more out of them. A power amp isn’t going to make them bass canons. I kept my A90 as a preamp for the AHB2 until recently

Thanks Raj, I suppose I just want to see what all the posts are about, and if there’s any actual proof or if its bigger thing makes bigger sound sighted influence. I’ve got a Denon AVR that can push 150 odd watt into lower impedance, is it worth me trying to hook that up? Is a modified cable with speaker taps mainly what is needed (and huge caution on volume?).

I got the power amp for the Susvara but it’s actually been great on all the headphones I’ve tried through it. Seemed to have the least impact on the LCD-5. Yes definitely use power amps and headphones with caution. Something like the LQI or FogCityAudio cables should get you started, though you can get small devices that sit in between which are neater

Check out @GoldenSound videos. He ABXs amps for testing and tries sus on basicaly everything he gets in. Tbh though, a good amp for sus is a fairly night and day difference. I did blind abx with them when i got them (@Skedra built me a custom switch box that can take the powrt to do it) and it was 100% a yiu need a couple seconds to tell the difference between under poweted and gobs of power

Thanks mate, which of his videos does he do the ABX in if you don’t mind linking an example? I’ve tried watching a few of his vids but I’ve not found ABX’ing done beyond mentioning he’s tried X on Y and it sounds cold / clinical / warm / engaging / musical / controlled etc.

He does it for all dacs as a way to confirm his initial thoughts. For amps he does abx but im not sure if its blind simply due to the limitations of most switch boxes. A major fsctir of why he bought this amp is that it allows abxing for dacs and pres.

@GoldenSound you written up your normal “testing procedure” of sorts anywhere?

For most devices, I’ll first let them warm up for a few hours, and then will start with some sighted tests. Just sitting and using the device as I usually would, though keeping other components in the chain consistent.
So if evaluating an amp I’d always use my main DAC for example, and if evaluating a DAC I’ll always stick to the same amplifier/headphone.

Previously my reference chain was HQPlayer → Holo May → Holo Serene → AHB2 → Susvara, however I’ve sold the Serene and AHB2 to help pay for the HM1, so I’ve been using the Ferrum OOR as my reference amp for a bit.

I will usually change the primary headphone I’m using for evaluation depending on the amp though.

Sighted Testing:
I’ll listen to the device by itself, making some notes as I go and getting a feel for it, and then I’ll move on to doing some sighted AB tests with other gear to make comparisons.
To keep things fair, for DACs, I’ll volume match to 0.01dB digitally, and for amps, I’ll volume match as close as I possibly can (the pot itself is the limit here, it’s pretty hard to make really really fine adjustments on many amps), and then will control volume using the preamp to ensure that the two amps remain level matched and any volume adjustment affects both.

I’ll then make some comparisons and again make a few further notes, swapping back and forth, sometimes quickswitching and sometimes longer periods. I find that there are some things I notice more when quickswitching, and some things that are more obvious when I suddenly switch to a different device after my brain/hearing has adjusted over a longer period to the first one.

Blind Testing:
Once I feel I’ve done enough of that and I feel I’ve gotten a good understanding of the device’s sound, I’ll do some blind testing. This is a device that Skedra and I (mostly Skedra) have worked on which allows for an unassisted blind ABX test.

It has both Stereo XLR-3, and XLR-4 inputs so can be used for either amplifiers or DACs, and has no measurable impact on distortion. It has a large bank of relays, which every time the A, B, or X buttons are clicked in the software, randomly switches a number of them, so that you can never tell if it has switched, or what it has switched to. It very effectively avoids any tells. The only thing you have to do is volume match.

Here’s a video from an older version that shows how it works:

I’ll do this to confirm whether I can correctly identify the devices I was comparing, and also note what characteristics that I’d noted down previously were now less obvious. Sometimes things that you may find in a sighted test are simply no longer present when you test blind. And for those characteristics, I assume that it must have been placebo and I do not discuss them in the review.

Though even for the characteristics that DO remain in the blind test, to be clear: You CANNOT actually use a blind test to evaluate a single characteristic, because so long as you can tell the difference between two devices for any reason (Amp A being warmer than Amp B for example), then placebo/expectation bias can still impact other factors.
If you KNOW you’re listening to Amp B in the blind test because it’s less warm, you might also expect to hear, and therefore hear an improvement in soundstage, regardless of whether it exists or not.

Blind tests aren’t a silver bullet for fully evaluating a device, but I find them personally quite helpful and they have helped me to eliminate some things which were likely caused by placebo/expectation bias.

Auxilliary testing:
Once the ‘main’ listening is out of the way, I’ll do any other testing I feel might be necessary. Testing different headphones on an amp, or testing a DAC with different sources etc.
Sometimes this can be influenced by the outcome of the last part which is the measured results. For example the Enleum AMP-23R on the measured results showed that it was limited in performance by hot inputs, and so I went back to try it with the input signal attenuated by 15dB and it did indeed sound better.

Finally, once all listening stuff is done, I’ll do the measurements. I prefer to do these last because I don’t want the measured results to influence what I hear or expect to hear.


I’ve mentioned ABX testing in videos but have not posted any videos of it for a few reasons.

Mostly, it’d just be creating drama and arguments. Those who are on one side of the fence, believing that DACs/Amps do in most instances sound different, would have no interest in watching a blind test (or would only want it for ammunition in internet arguments), and those on the other side who believe most DACs/Amps sound the same would not be convinced by a video I provided anyway, and would simply argue that the test was flawed or that the results were falsified.


well the new a90d has more low end so probably make the susvara sound more fun. A90 has enough power but other high quality amps do sound better in my opinion

the A90 is a competent amp for a lower end HP but like a toy for the susvara

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Thanks for your detailed post on your method! Always appreciated.
There are probably quite a few like myself who are more objective, who would benefit vastly from even just a couple videos showing the ABX test being passed as it gives reassurance that at least some reviewers that aren’t being influenced by biases (some of which they may not even realise). There’s plenty of snake oil in this hobby, so having something like this as a method of giving back confidence would be a good thing.

Having said that, I can definitely see however why you don’t want to open yourself up to both sides going crazy and you having to defend yourself.

I’ve been digging back into the Susvara lately and made some additional EQ. For anyone who has one and is willing to tinker a bit, give this a shot and let me know what you think.



I cant imagine using EQ on my susvara…I have had 2 susvara over the years and never even imagined it needing EQ

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It sure doesn’t. But nothing wrong with giving it a try.


If you have a Roon version I’ll give it a try just to see what it adds. Don’t feel like I need one tbh but if it impoves something why not