Sennheiser HDV-820 USB DAC & Headphone Amp Review

[Labjr]

I can only imagine what is being said! ASR has turned the entire review industry on it's head. I don't read many other reviews anymore. But I make fresh buttered popcorn for ASR. (Sometimes I choke on it!)

 

[Soniclife]

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.

Can you explain why it was done deliberately, and if it would be a good thing if implemented well

 

[August]

Can you explain why it was done deliberately, and if it would be a good thing if implemented well

I think that's just because they use 6120 on the amp chip.

 

[solderdude]

Can you explain why it was done deliberately, and if it would be a good thing if implemented well

Yes, TPA6120 is used balanced. Each output has 10 Ohm close to the IC (for technical reasons) and after that they split up the signal again using 10 Ohm resistors to the different output connectors. This makes the output R balanced at 40 Ohm.
For SE the output R is 20 Ohm.
Because one can use more than one output at the same time and wanted to comply to the TPA specifications to maintain stability even when using special high capacitance headphone cables.

 

[Veri]

Wait, this is a $2400 TPA6120 amp? Gosh.

 

[Rigel]

Hello. Thanks Amir for the review.

I am partly surprised and partly not. I explain.
I have the previous version, the HDVD800 that I bought to combine it with the HD800 (300 Ohm). I really bought the set. It has a different DAC and probably worse than the HDVD820 ES9018
In the case of the HDVD800, I saw two details that I didn't like. One was the DAC, a PCM1792 that I have not used, but especially the switching power supply it has. Appreciate improvements with the change for a linear power supply and the HDVD820 also has the same or very similar.
As for the sound, very happy with the couple using an external analog audio source.

 

[Dialectic]

Hello. Thanks Amir for the review.

I am partly surprised and partly not. I explain.
I have the previous version, the HDVD800 that I bought to combine it with the HD800 (300 Ohm). I really bought the set. It has a different DAC and probably worse than the HDVD820 ES9018
In the case of the HDVD800, I saw two details that I didn't like. One was the DAC, a PCM1792 that I have not used, but especially the switching power supply it has. Appreciate improvements with the change for a linear power supply and the HDVD820 also has the same or very similar.
As for the sound, very happy with the couple using an external analog audio source.

Switching power supplies and the PCM1792 chip are capable of superb performance. The deficiency here was in implementation, not parts selection.

 

[Alexander Gödde]

This really makes you wonder how "incredible" the HE 1 sounds... or doesn't perhaps.

This measurement - https://www.dropbox.com/s/fk4qx1jjjjrl37n/Sennheiser HE1.pdf?dl=0 - indicates that the HE 1 is good. That's a really good frequency response, and I'd expect low distortion as well. So while I can't imagine it's remotely worth the price based on performance, it at least appears you're getting a headphone which is enjoyable without you having to engage your powers of self-delusion.

 

[vkvedam]

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:

View attachment 42566​

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:

View attachment 42567​

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:
View attachment 42568

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:
View attachment 42569

Signal to noise ratio is not as good as it should be for this price range:
View attachment 42570

Jitter is very good:
View attachment 42571

Multitone test shows low intermodulation distortion:
View attachment 42572

But when we measure that relative to level, we see the clear signature of ESS DAC chip:
View attachment 42573

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:
View attachment 42574

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:

View attachment 42575

This is not good. There are a lot of amps that do better:
View attachment 42576

Signal to noise ratio is nothing to write home about:
View attachment 42577

View attachment 42578

Expect to hear some hiss with sensitive IEMs and headphones.

Frequency response is dead flat and hence excellent:
View attachment 42579

But this doesn't mean you get flat response from your headphones because of this:
View attachment 42580

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:
View attachment 42581

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:
View attachment 42582

This is just bad for a desktop headphone amplifier.

Comparing 1/4 "unbalanced" headphone output to "balanced" XLR Output we get:
View attachment 42583

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:
View attachment 42584

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:
View attachment 42585

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.

------------
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/

Holy cow! Wasn't expecting that especially coming from Sennheiser as they make some of the best transducers.

 

[Rigel]

Switching power supplies and the PCM1792 chip are capable of superb performance. The deficiency here was in implementation, not parts selection.

I've taken it for granted, that's what I meant. Obviously not all switched power supplies are the same.

 

[Nango]

Holy cow! Wasn't expecting that especially coming from Sennheiser as they make some of the best transducers.

.... really? Who knows!

 

[anmpr1]

Wasn't this amp specifically designed to work with the HD800?

If you surf to Sennheiser they say the thing is meant to ...complete the Sennheiser audio experience and perfectly complement its high-end audiophile headphone range for the ultimate acoustic performance.

But then...The perfect partner for reference-class headphones. That is, if you are lucky enough to possess headphones capable of turning the extremely high-quality audio signal delivered by the HDV 820 into an aural quality just as supreme.

So on the one hand, yes, on the other, no. It's not like, say, Stax, where you only use their box with the headphone.

 

[FourT6and2]

For those saying this unit is broken and should be sent in for repair, I will certainly contact Sennheiser. However I've never heard any issues with it... Maybe something broke in shipping for testing?

 

[vkvedam]

.... really? Who knows!

HD800, HD650 and HD600 are unequivocally regarded as some of the best, you might not agree though

 

[Soniclife]

Yes, TPA6120 is used balanced. Each output has 10 Ohm close to the IC (for technical reasons) and after that they split up the signal again using 10 Ohm resistors to the different output connectors. This makes the output R balanced at 40 Ohm.
For SE the output R is 20 Ohm.
Because one can use more than one output at the same time and wanted to comply to the TPA specifications to maintain stability even when using special high capacitance headphone cables.

Your original statement read to me that the higher than normal impedance was a desired result, not just where it ended up from their design choices. I'm trying to understand if that is what you meant.

 

[TonyNL]

Likewise, I have a Stax SR-007 and 507. I only have the srm-353S for amplifier. For years, people keep telling me I need a better amp. But most recommendation are tube amps or custom amp that are assembled based on a design by some legendary designer. One thing in common about these custom amps beside the designer is it's peppered with hefty amount of audiophile terms (e.g. capacitor brand etc) and heavy dose of subjective sighted reviews.

The specs even does not show any improvement and sometimes lesser output power. But none has done any basic measurements. If you ask for one you get ignore.

So yeah I very much like one of these amps get measured ASR style.

Are you talking about the Blue Hawaii Special Edition? I own a Stax L700 + SR353x, which is my best sounding combo in house at this moment, but I like the Stax so much that I want to upgrade to 009s with a BHSE. I had only limited experience with 009s and never experienced the BHSE in real. Do you still recommend me to give it a try?

 

[solderdude]

Your original statement read to me that the higher than normal impedance was a desired result, not just where it ended up from their design choices. I'm trying to understand if that is what you meant.

I guess I should have explained it was a technical decision that is of no real consequence of the sound for the HD600/HD650/HD800/HD800S and HD820 which is what it is designed for.
Also I sometimes get feedback users of the same headphones often prefer them on the 33Ω setting (instead of 0.2Ω or 120Ω) on certain configurable amps.
The higher resistance for these headphones isn't an issue.

 

[amirm]

If the high output impedance is their only nod to create a better match for their headphones, then they should have made a low impedance amp and then put a switch to put that resistance inline.

 

[NTomokawa]

The classic Norio reaction: Yikes.

That being said, does it have any safety certifications? Being a German brand, I expected a TÜV mark, but there's nothing of the sort on the back panel.

 

[suttondesign]

Sennheiser gets what it deserves for selling such a mediocre product for such a sky-high price based on nothing but its reputation. Thanks to this site, it's reputation just took a big hit.