Review and Measurements of RME ADI-2 DAC

[Blumlein 88]

Adding an input zero/snubber circuit to prevent HF signals beyond the feedback's ability to compensate from going through the amplifier has been around "forever". I used the idea decades ago for a new differential amplifier circuit topology (hey, even hairy-knuckled engineers invent something now and then). I do not remember which ones, but some amps targeting ESLs included the same circuit to help compensate their HF capacitive load.

I had this in mind when I was looking at the explanation. I've got ESL's and can see where it would be useful in some cases with them.

Oddly, one of the best amps for ESL's are the Spectral super wide bandwidth amps. I do wonder if they were sort of accomplishing this when they went with MIT interconnects and speaker cables that rolled off ultrasonics like a 1st order filter. At one time it was implied your warranty was only good with MIT cabling. Cables do matter when your bandwidth is a couple megahertz maybe?

 

[Frank Dernie]

you said that right...for 2 grand or more, a dac should come in at full fighting trim, primed and ready to go.
i understand something that costs a hundred bucks or so saying this..

I am quite sure Keith was taking the mickey. Linear supplies are not necessarily better.

 

[Dro]

I have to say this really made me interested in getting a Benchmark amp, but they no longer sell their HPA-2 standalone. I also won't get one of their DACs with the integrated amp because the RME DAC has features they don't offer.

Funny how that works out. They sparked my interest, yet do not have a product I actually want to buy.

 

[Purité Audio]

I am quite sure Keith was taking the mickey. Linear supplies are not necessarily better.

I was just surprised when the Mytek designer publicly stated that his dac as sold could be improved upon, I would have expected a fully formed implementation in the first instance.
Either he is pandering to the ‘audiophile’ crowd or doesn’t know how to design power supply filtration/regulation.
Keith

 

[XpanD]

I was just surprised when the Mytek designer publicly stated that his dac as sold could be improved upon, I would have expected a fully formed implementation in the first instance.
Either he is pandering to the ‘audiophile’ crowd or doesn’t know how to design power supply filtration/regulation.
Keith

The audiophile crowd thing would make sense, also going by this:

On the second harmonic clipping, he says this is due to the attenuator (volume control) circuit which was intended to have a "warm" sound. Shutting off the volume control makes most of the second harmonic distortion to go away (graph in blue):

I guess this is their attempt to create the "tube" sound with those high levels of second harmonic distortions and at any rate, cater to subjective audiophile needs this way. Not my cup of tea. I want my volume control to be fully transparent and not inject gobs of second harmonic distortion into the path. If I want to distort it, I will do it elsewhere, thank you very much.

Pictures died, but yeah. Kind of a shame, because it looked like a solid device to me otherwise. Wonder if this was changed any in the new Brooklyn+...

 

[Sythrix]

I have to say this really made me interested in getting a Benchmark amp, but they no longer sell their HPA-2 standalone. I also won't get one of their DACs with the integrated amp because the RME DAC has features they don't offer.

Funny how that works out. They sparked my interest, yet do not have a product I actually want to buy.

They have the HPA-4 for 3 grand, shipping in June.

I am extremely interested in getting some comparisons between this and the Massdrop THX 789, because they both use THX technology, although the Benchmark uses the more advanced design (THX-888). Especially considering this new test on measuring at the connection with phones connected. I'd like to see how their own new implementation works, but also how the Massdrop model fares. Benchmark seems to have conveniently forgotten their own adage to not care about balanced connections, so will they too conveniently forget about the methods described here if it isn't already a part of the THX design?

I wonder if anyone here will be able to get the HPA4 to send to Amir. I plan on sending my Massdrop THX 789 to him when it arrives in ~October, if no one else has already made plans.

 

[Rod]

Well mine just got shipped. I haven't commented on the tests because of my limited knowledge, theirs nothing I can add so sometime its better just to shut up and listen. But I have been paying attention and trying to learn what the test are showing.
Retirement has been great, but I keep trying to find things to do. Collected antique zippos for awhile, started making my own mechanical watches and learning how to take them apart and service them(clean and oil) and now on to headphone amps/dacs(again). I just keep bouncing around. Time for a vacation I guess. last one I ended up living in south-east asia for a couple years on an island. Beautiful over there.

 

[amirm]

I wonder if anyone here will be able to get the HPA4 to send to Amir. I plan on sending my Massdrop THX 789 to him when it arrives in ~October, if no one else has already made plans.

Thanks. I have tentative plans to buy the Monprice combo of THX+DAC when it comes out in June. Assuming it comes out in June!

I don't know when it became fashionable in this part of the market to pre-announce products so far in advance.

 

[Sythrix]

Thanks. I have tentative plans to buy the Monoprice combo of THX+DAC when it comes out in June. Assuming it comes out in June!

I don't know when it became fashionable in this part of the market to pre-announce products so far in advance.

Also seriously considered the Monoprice one, because it uses dual of the brand new AK4493 DACs. Although, a representative for THX at Massdrop said it was not truly balanced, but I don't know the extent of that, as there seems to be some confusion with what Monoprice was telling people on the website and the representative. What clinched my decision was that it doesn't seem you can use it as a pure balanced DAC output, with it only accepting balanced input, although that would lead credence to what they were saying over at Massdrop about it not being actually balanced.

Ended up springing for the RME here instead, to use mostly as a pure DAC. Every month the Monoprice THX seems to go back a month in turn. Hope they quit pushing it so you can get your hands on one, as I'm still eager to see how it performs.

 

[Dro]

I totally missed what this THX stuff is all about. Not in the market for a 2900 USD only-amp device either though. That money would be spent on headphones. Considering I don't run Grados, I can probably live with -80 dB THD at low frequencies if I use the ADI2-DAC. It does everything else I want:

• IEM output with extra low noise
• Digital volume control
• Auto loudness
• Crossfeed
• PEQ for left and right channel
• Presets so I can switch between headphones quickly
• Remote control
• Not Schiit

 

[mindbomb]

Benchmark seems to have conveniently forgotten their own adage to not care about balanced connections, so will they too conveniently forget about the methods described here if it isn't already a part of the THX design?

I don't think the hpa4 has balanced headphone output. It has the 4 pin xlr connector just for the slightly reduced output impedance and the reduced crosstalk, but not double the voltage.

 

[Sythrix]

I don't think the hpa4 has balanced headphone output. It has the 4 pin xlr connector just for the slightly reduced output impedance and the reduced crosstalk, but not double the voltage.

You may be right. It could be that they just use balanced for line level input and output. I can't find anything that says the headphone output is balanced. Shocked to see the XLR headphone connection on a Benchmark.

I thought the main purpose of the 888 was the fully balanced signal path. Perhaps it was just convenient for their price range. "We've got the best of the best!... $3000"

 

[Rthomas]

@amirm

Thanks for the review! If the RME measures about as well as possible is there any reason to spend twice as much on the Benchmark DAC3 series?

Wouldn't it be impossible to distinguish between the DAC section of these devices?

Hope someone sends you a Benchmark DAC2 or DAC3 to compare. Surely a few members must have one or the other....

 

[amirm]

@amirm

Thanks for the review! If the RME measures about as well as possible is there any reason to spend twice as much on the Benchmark DAC3 series?

Well, you can see that I did not opt to buy the Benchmark so you know my answer.

That said, I do like to measure it still. Hopefully we can do that one day or more people like you donate to the site so that I can purchase it.

 

[Dro]

@amirm did you do any more THD measurements with real headphone loads (no matter which amp)?

 

[amirm]

@amirm did you do any more THD measurements with real headphone loads (no matter which amp)?

Yes, see the Schiit Lyr and Magni 3 review here: https://www.audiosciencereview.com/...-of-schiit-lyr-tube-headphone-amplifier.2451/

And Chord Hugo 2: https://www.audiosciencereview.com/...hord-hugo-2-dac-and-headphone-amplifier.2349/

 

[Dro]

Nice! Whit is the scale with the Schiit amps?

 

[amirm]

It is the distortion specified in percentage. You can use this nice calculator to convert them to dB: http://www.sengpielaudio.com/calculator-thd.htm

I will try to be more consistent in the future.

 

[amirm]

Actually, it was easy enough to convert them myself. Here is the raw graph:

I probably should re-run them to make sure everything is measured the same.

 

[Dro]

I will try to be more consistent in the future.

Some things to consider:

• Which headphones to test? HD650 seems like a popular choice with low distortion, the Grados for high distortion. One magnetostatic headphone should also be included in my opinion.
• Do you test at a fixed output voltage or SPL (per headphone)
• Maybe measure only THD, not THD+N (Benchmark did that in their whitepaper)