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Sennheiser HDV-820 USB DAC & Headphone Amp Review

amirm

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This is a review and detailed measurements of Sennheiser HDV-820 DAC and Balanced Headphone Amplifier. It is on kind loan from a member. The HDV-820 costs US $2,400 with Prime shipping from Amazon. Settle down! I know you can't afford it but maybe it is good.

While the enclosure itself is not that unique, Sennheiser nails the feel and look at the controls:

Sennheiser HDV-820 USB DAC and Headphone Amplifier Audio Review.jpg

Usability is not quite there though. I literally had my thumb pinched between the volume control and input selector. In reverse, trying to change the inputs, your fingers may hit the volume control.

Other than that, the volume control, selector and especially the power button with its white LED ring are quite nice. The light pipes for the input indicators bleeds to adjacent labels which is unfortunate.

As you see, you have every type of headphone output and then some. Back panel shows a lot of inputs and outputs as well:
Sennheiser HDV-820 USB DAC and Headphone Amplifier Back Panel Connectors Audio Review.jpg

Nice to see analog inputs on a DAC+Amp combo.

Lacking is AES digital input in this price range.

There are no gain controls. Just turn up the volume and it will keep getting louder. This likely will hurt its signal to noise ratio.

DAC Audio Measurements
As usual, we start with our dashboard with XLR Output:
Sennheiser HDV-820 USB DAC and Headphone Amplifier Audio Measurements.png


XLR output seems to be tied to headphone out as it could go as high as 11 volts output! I dialed it down to 4 volt for above measurement. Distortion+noise is in the competent range:
Best Combination DAC and Headphone Amplifier Review.png


Signal to noise ratio is not as good as it should be for this price range:
Sennheiser HDV-820 USB DAC and Headphone Amplifier Dynamic Range Audio Measurements.png


Jitter is very good:
Sennheiser HDV-820 USB DAC and Headphone Amplifier Jitter Audio Measurements.png


Multitone test shows low intermodulation distortion:
Sennheiser HDV-820 USB DAC and Headphone Amplifier Multitone Audio Measurements.png


But when we measure that relative to level, we see the clear signature of ESS DAC chip:
Sennheiser HDV-820 USB DAC and Headphone IMD Amplifier Audio Measurements.png


We have the classic "ESS IMD Hump" and higher noise in general.

Digital In Headphone Amp Measurement
The headphone amplifier works with analog input and output. But I thought I measure it in combo with the DAC first:
Sennheiser HDV-820 USB DAC and Headphone Amplifier THD into 300 Ohms Audio Measurements.png


We have good bit of power but disappointing distortion and noise level. Above is with the volume turned down. The higher the volume, the higher the noise level. They should have implemented a gain setting.

Headphone Amplifier Measurements
For these tests I fed the HD-820 with XLR Input (in the back -- don't confuse this with XLR Headphone out). I started with 1/4 Headphone output:

Sennheiser HDV-820 Headphone Amplifier Audio Measurements.png


This is not good. There are a lot of amps that do better:
Best Headphone Amplifier Review 2019.png


Signal to noise ratio is nothing to write home about:
Sennheiser HDV-820 Headphone Amplifier Signal to Noise Ratio Audio Measurements.png


most quiet hiss free headphone amplifier.png


Expect to hear some hiss with sensitive IEMs and headphones.

Frequency response is dead flat and hence excellent:
Sennheiser HDV-820 Headphone Amplifier Ferquency Response Audio Measurements.png


But this doesn't mean you get flat response from your headphones because of this:
Headphone Amplifier Output Impedance Measurements.png


45 Ohm impedance means that unless your headphone has a flat response (e.g. planar magnetics), its frequency response is going to change. This may make it sound better or worse. It also means lots of power will be wasted into low impedance headphones. We will see this effect shortly.

Here is power vs distortion into 300 ohm load:
Sennheiser HDV-820 Headphone Amplifier Power into 300 ohm Audio Measurements.png


Wow. The gap in noise and distortion is quite massive relative to our state-of-the-art headphone amps we can get today for as little as US $99. We do have lots of power though so dynamic range won't be an issue.

Issue you will have with low impedance loads like 33 ohm:
Sennheiser HDV-820 Headphone Amplifier Power into 33 ohm Audio Measurements.png


This is just bad for a desktop headphone amplifier.

Comparing 1/4 "unbalanced" headphone output to "balanced" XLR Output we get:
Sennheiser HDV-820 Headphone Amplifier Power into 50 Balanced ohm Audio Measurements.png


I was surprised how much cleaner XLR output was. But then it got distortion even more than 1/4 headphone out. You do get four times more power with XLR output which is always good to have.

Sweeping the input frequency and measuring distortion and noise we see quite a rise:
Sennheiser HDV-820 Headphone Amplifier THD vs Freq Audio Measurements.png


Distortion rises to almost 0.2% at 20 kHz! This is crazy high for any amp let alone an expensive one.

Headphone Listening Tests
I started my testing with the 25 Ohm MrSpeakers Ether CX headphones. That was a mistake. The HDV-820 produced the worst sound I have heard from them by far. It was distorted, lacked bass and dynamics and overall screwed up. Yes, that is a technical term. It is the opposite of not screwed up.

The situation drastically changed with Sennheiser HD-650 using 1/4 headphone jack. There was tons of power and dynamics. And whatever change the HDV-820 made in my short listening, seemed to be a positive.

Thermal Stability
Per our recent policy, I am testing devices for a few minutes until they get warm to see how they behave on distortion+noise. This is the HDV-820:
Sennheiser HDV-820 USB DAC and Headphone Amplifier Warm Up Measurements.png


Yes, you are seeing what I am seeing. The channel in blue had a mind of its own just sitting there. Performance degraded as much as 5 dB on its own. There was no correlation with temperature during this 25 minute test. Probably not audible but sure demonstrated lack of good engineering.

Conclusions
At the US $2,400 price point I expect perfection. Sadly are not remotely there with Sennheiser HDV-820. The DAC is fine but stability is not. The headphone amp with its high impedance and hence low power/higher distortion makes this amp suitable for a small set of headphones. With many headphones you are going to experience a different sound than the headphone is meant to produce.

I think Sennheiser should take out the amp, license a THX amp and then they would have something proper. Even then, US $2,400 is a lot of money.

Needless to say, I can't recommend the Sennheiser HDV-820.

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As always, questions, comments, recommendations, etc. are welcome.

We probably not going to get sun for another 5 months here. Depression will likely set in soon and heaven knows you don't want me depressed. The only solution to it in my book is lots of money in my pocket. So please donate as much as you can using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
 

Labjr

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Why is it so difficult to design a reference DAC with a reference headphone amp?
 

JohnYang1997

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I think the industry lacked a reference performance in the past. They decided what was good enough and went for it.
Well they got reference performance from datasheets.
 
OP
amirm

amirm

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Well they got reference performance from datasheets.
True but consumers don't read datasheets. They do read our graphs now. :) So the game has changed. They either get with it or get out of the market.
 

FourT6and2

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This is my unit. While the test results are surprising all I can say is it still sounds good lol. I've had it for about six months and compared it side-by-side with a few other amps including the Benchmark HPA4, Aune S7 Pro, Sony TA-ZH1ES, THX 789, and a few others. Headphones have been Sony MDR-Z7M2, Sony MDR-Z1R, Focal Elegia, Focal Elear, Sennheiser HD820, and Meze Empyrean.

Regardless of measurements, it's been nothing but clear and powerful for me. But my setup hasn't been very complex. Just running laptop USB out to the internal DAC and plugging some headphones in and rocking out. I did briefly try some other headphones like the Audeze LCD4, Abyss Diana Phi, and Abyss 1266 TC. Granted those didn't sound their best with this amp.

I do have the Benchmark setup now and I'm sticking with that since it's a proven worry-free rig. But I haven't had any problems with the HDV-820. In fact, I prefer this unit to every other amp I tested except the Benchmark and THX 789, which do sound better.
 
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Vovgan

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I think the industry lacked a reference performance in the past. They decided what was good enough and went for it.

Yes and no. They had a reference in its predecessor - HDV-800. Long ago I bought HDV-800 together with my first headphones, only to discover later that it was criticised in many Internet forums for it’s poor DAC. It seems that Sennheiser took note of that criticism and improved the DAC part but didn’t bother to check the amp. As of now this is their flagship product (except HE 1) for several years running, they should have long ago figured out and fixed the problem with the amp by releasing a newer model. Shame for poor performance in objective tests, especially given the price tag. But still more shame for being content with it, sitting on their hands for several years and still selling it as their premium model at a premium price.
 
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digicidal

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This really makes you wonder how "incredible" the HE 1 sounds... or doesn't perhaps. :rolleyes: I think it's fairly clear that this was only tested with their own headphones, that is if it was tested at all. Especially considering that wandering channel I wonder if this specific sample is defective? Although other aspects would indicate that there are issues at a fundamental level as well.
 

headwhacker

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This is my unit. While the test results are surprising all I can say is it still sounds good lol. I've had it for about six months and compared it side-by-side with a few other amps including the Benchmark HPA4, Aune S7 Pro, Sony TA-ZH1ES, THX 789, and a few others. Headphones have been Sony MDR-Z7M2, Sony MDR-Z1R, Focal Elegia, Focal Elear, Sennheiser HD820, and Meze Empyrean.

Regardless of measurements, it's been nothing but clear and powerful for me. But my setup hasn't been very complex. Just running laptop USB out to the internal DAC and plugging some headphones in and rocking out. I did briefly try some other headphones like the Audeze LCD4, Abyss Diana Phi, and Abyss 1266 TC. Granted those didn't sound their best with this amp.

I do have the Benchmark setup now and I'm sticking with that since it's a proven worry-free rig. But I haven't had any problems with the HDV-820. In fact, I prefer this unit to every other amp I tested except the Benchmark and THX 789, which do sound better.

Problem is what make one thing sound good for one person is not necessarily the same for another. Subjective comments is really a poor indicator.
This is another proof the industry has been churning out mediocre products and still make big profits.
 

August

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Someone still calls it the "set" with hd820 as "unparalleled sound":)
 

maxxevv

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Someone still calls it the "set" with hd820 as "unparalleled sound":)

I actually tried the HD820 with the HDV-820 at CanJam, I wasn't that impressed with the end result.

The Focal Stellia with separate brand amp ( can't recall which amp that was) at the show was a "better" sounding headphone setup using my own sound tracks.
 

AnalogDE

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I actually tried the HD820 with the HDV-820 at CanJam, I wasn't that impressed with the end result.

The Focal Stellia with separate brand amp ( can't recall which amp that was) at the show was a "better" sounding headphone setup using my own sound tracks.

I just tried the same setup today at the Sennheiser store in San Francisco and I wasn’t impressed with it either. I’m thinking my Sabaj D5 with HE4xx sounds better.
 

solderdude

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I would say one channel is defective for this amp and would send it in for service (under warranty) based on these measurements.

Furthermore I should mention that this DAC-Amp is specifically designed to drive 300 to 600 Ohm headphones and the output resistance is deliberately this high.
For this reason a 50mV is less important as the 300 Ohm headphones it is specifically designed for are not as voltage sensitive as IEM's and low impedance headphones.

That said I would certainly not recommend this DAC-Amp combo, most certainly not for driving lower than 300 Ohm headphones.
The price is way too high for what it offers.
 

maxxevv

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I just tried the same setup today at the Sennheiser store in San Francisco and I wasn’t impressed with it either. I’m thinking my Sabaj D5 with HE4xx sounds better.

As much as I enjoy the output of the KTB + Atom / HPA-3B for the HE4XX and HD6XX, I can't say that they are an apples to apples comparison, simply because the HD820's are closed backs and the HE4XX being open.

Will have to revisit the HD820 headphone again some day with some other amp and see how it fares instead.

As Franz has highlighted, the HDV820 seems to be catered to a very narrow band of operational use, so its value preposition is definitely not attractive.
 

trl

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I wasn't expected such a low-level of performance from the internal headamp. Even if it was designed to drive high-impedance cans only, it still measures worse that many cheaper headamps. :(

However, at least as a DAC it measures very well, although it's way too pricey to pay for it as a standalone DAC only.
 

Cortes

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The first time I saw the price tag of this amp I was shocked. I'm not surprised with the results.

There is niche market in the amp electrostatic sector with Stax , KGSS, headamp and others, and many models have sky level prices (>4000$).
In some cases promoting all the audiophile mythology. I hope Amir gets them some day, I expect some horror.
 

filo97s

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This really makes you wonder how "incredible" the HE 1 sounds... or doesn't perhaps. :rolleyes: I think it's fairly clear that this was only tested with their own headphones, that is if it was tested at all. Especially considering that wandering channel I wonder if this specific sample is defective? Although other aspects would indicate that there are issues at a fundamental level as well.
it's a tube amp so expect to be much worse than this. Still, it's designed around that specific headphone so I hope the combo will sound very well.
You know, there are two schools of thought, the measurement-and-precision one which is the one I like, and the euphonic pleasing distortion. The latter is quite difficult to rate through a graph.
 
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