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Measurements of RME ADI-2 DAC and Headphone Amp

JohnYang1997

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Hi! After searching for a modern audio interface with a good headphone amp and a parametric EQ, I settled on the ADI-2 DAC. Just wanted to share some of my impressions and experiences:

1. "Driverless" operation is still clunky on Windows 10 1809 even with the latest firmware 26/30. Windows' sound control panel disallows sample rate/format selection, locked at 44.1 KHz and 32 bits. DirectSound works, but "exclusive mode" aka WASAPI is clunky: Foobar2000 in WASAPI mode produces various clicking and beeping noises, and sometimes either errors out with "unsupported format" when switching to tracks with different sample rate, or "successfully" changes the sample rate (as confimed by the ADI-2 DAC display) but produces heavily distorted sound. MPC-HC, on the other hand, works OK in "exclusive" (aka WASAPI) mode, changes the sample rate and all, but when it enters said "exclusive" mode, all other applications that were producing sound at that moment crash or display error messages. While I'm hoping this is all just Windows being Windows, and not a problem with the ADI-2 DAC, still it is a bit disappointing :(

2. Keeping the above in mind, after installing the official RME drivers, everything works great through either DirectSound or ASIO, albeit WASAPI stops working completely. I guess I can live with that, as long as RME continue providing their drivers for all the new Windows versions that Microsoft pushes every six months :)

3. One other thing that was not clear to me from all the reviews and product descriptions, is that the ADI-2 DAC can't use all of its outputs independently. It only toggles between them, either manually or automatically. Furthermore, the "phones" and "IEM" outputs are not separated -- they are both active at the same time and share volume control. This is not a huge problem for me personally, though something to keep in mind if you're considering this device and want to use all outputs independently and at the same time. :confused:

4. The controls are very responsive, the display is a fairly high-resolution IPS panel. The UI probably could be a bit more easy to navigate, but it's fully functional, fast enough to navigate, and far from "horrible" like some reviews say. :)

So far, when it does work as expected, there are no audible sound quality problems :)
The wasapi exclusive thing is very normal or it's what it should be. Exclusive means all other applications can't access the interface. It pretty much acts like asio.
And as after installing driver asio works just fine I don't see anything wrong here. Just as it should be. Wasapi shouldn't be a part of the design. So it may break.
So you can use windows audio for casual use and asio for critical use.
 
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The wasapi exclusive thing is very normal or it's what it should be. Exclusive means all other applications can't access the interface. It pretty much acts like asio.
And as after installing driver asio works just fine I don't see anything wrong here. Just as it should be. Wasapi shouldn't be a part of the design. So it may break.
So you can use windows audio for casual use and asio for critical use.
Hi! I agree that WASAPI is just classic microsoft not caring enough . They could continue to accept audio streams from "shared-mode" applications and just seamlessly discard them when an "exclusive-mode" application enters the field. No need to crash the DirectSound applications or spit erros at them, which they spit at their users in turn. From my point of view as a programmer, that's just some lazy coding on Microsoft's behalf. Poor handling of WASAPI in Foobar2000 also kinda serves as evidence that the API is not as simple to use and foolproof as it should be. Oh well, it's microsoft, what can we do :)
By the way, ASIO applications work fine alongside DirectSound applications, I can hear sound from both at the same time, so I guess either the ASIO driver or the hardware does the mixing. Sample rate dictated by an ASIO application is reflected in Windows' sound control panel, though still can't be changed from there manually. So, in this regard, WASAPI is nothing like ASIO, actually it's much worse :)

I partly agree with your point about ASIO+DirectSound, but the problem here is it will only work as long as RME continue providing support in the form of updated drivers for the never-ending stream of Windows updates. I learned that the hard way when my E-MU 1616m just refused to work anymore on the recent 1903 windows "feature update". And E-MU is defunct, so there will be no new drivers :(

On the other hand, I've seen reports somewhere earlier in this thread that at least with the latest firmware the ADI-2 DAC should work fine "driverless" on Windows, including manual selection of output formats for DirectSound, up to 32/384. That isn't the case for me, sadly, which is slightly disappointing :(
 
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when it enters said "exclusive" mode, all other applications that were producing sound at that moment crash or display error messages.
That’s what Exclusive Mode means. Windows grants one app complete control over output. Smart apps relinquish control when playback is paused. Dumb apps have to be closed to allow other apps to output sound.

Exclusive mode facilitates bit-perfect playback because the Windows mixer and other apps are not affecting output.
 

Music1969

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The DAC still oversamples via its digital filter (linear/minimum phase sharp/slow ...) as per the AKM datasheet.
Except if fed DSD and ‘DSD Direct’ is enabled. A few HQPlayer users use it like this.

I think also when fed PCM705/768kHz also - with up-sampling software.
 

daftcombo

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By 8x upsampling (not: resampling, at least not in an asynchronous fashion), digital filtering, then analog filtering (both in the chip and in the analog section).
I didn't realize the different meaning of resampling and upsampling before, thanks!
 

Jim777

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1. "Driverless" operation is still clunky on Windows 10 1809 even with the latest firmware 26/30. Windows' sound control panel disallows sample rate/format selection, locked at 44.1 KHz and 32 bits. DirectSound works, but "exclusive mode" aka WASAPI is clunky: Foobar2000 in WASAPI mode produces various clicking and beeping noises, and sometimes either errors out with "unsupported format" when switching to tracks with different sample rate, or "successfully" changes the sample rate (as confimed by the ADI-2 DAC display) but produces heavily distorted sound.
I recently got on the ADI-2 DAC bandwagon, and had similar issues (control panel locked, etc.), but found that they weren't really RME's fault:
- If you decide to uninstall RME drivers to try WASAPI again, there is something broken that might get fixed by going to Device Manager, update the RME device driver, select your own, Windows class 2.0. It will still show up as RME in the device manager, but it will work right now.
- Foobar2000 has to be in push mode instead of event (or try increasing the default latency for event mode by 4x in the advanced settings).
- Even then, Foobar2000 WASAPI support is broken, I could get 16 and 24 bit tests to pass, but not 32. And other issues. As much as I like F2k, forget about it for WASAPI.
- I got a trial of JRiver, that one passed 16,24,32 at all sampling rates (WASAPI).
 
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I recently got on the ADI-2 DAC bandwagon, and had similar issues (control panel locked, etc.), but found that they weren't really RME's fault:
- If you decide to uninstall RME drivers to try WASAPI again, there is something broken that might get fixed by going to Device Manager, update the RME device driver, select your own, Windows class 2.0. It will still show up as RME in the device manager, but it will work right now.
- Foobar2000 has to be in push mode instead of event (or try increasing the default latency for event mode by 4x in the advanced settings).
- Even then, Foobar2000 WASAPI support is broken, I could get 16 and 24 bit tests to pass, but not 32. And other issues. As much as I like F2k, forget about it for WASAPI.
- I got a trial of JRiver, that one passed 16,24,32 at all sampling rates (WASAPI).
Hi! Thanks for all the suggestions, really appreciate it! But the plot thickens :)
So, I installed 1903 again, to see if it will work any better. At first it was the same story (without RME drivers), but somehow after several restarts (without fiddling with audio drivers) Windows will now let me select sample rates from 44.1 to 384 (only 32 bit, though, which is fine) o_O WASAPI also "works" in its strange way, but whatever. So something is definitely broken, probably in Windows (wouldn't that be a surprise, lol). Or maybe there is some very subtle error in how the ADI-2 DAC communicates over USB. The latter in theory would be fixable through a firmware upgrade, so there is hope :)

Anyway, driver issues on Windows aside, the ADI-2 DAC is actually pretty amazing. Though if it could have all outputs active and independently controlled at the same time, it would be even better... :)

Concerning Foobar2000, well, maybe it's time to try the alternatives. I hear AIMP is nice :)

Btw, would be interesting to hear if Linux and macOS users have had any problems with the device?
 
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Frank Dernie

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Anyway, driver issues on Windows aside, the ADI-2 DAC is actually pretty amazing. Though if it could have all outputs active and independently controlled at the same time, it would be even better...
It would need multiple volume controls then. Is there a device which has such a function? I have never heard of one but I very rarely use headphones so no problem for me.
I use a Mac and haven't had any unexpected or faulty behaviour.
 

Rja4000

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Anyway, driver issues on Windows aside, the ADI-2 DAC is actually pretty amazing. Though if it could have all outputs active and independently controlled at the same time, it would be even better... :)
The Pro has separate controls for 2 headphones or for Main + Headphone (since it has 2 DACs)
 
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It would need multiple volume controls then. Is there a device which has such a function? I have never heard of one but I very rarely use headphones so no problem for me.
I use a Mac and haven't had any unexpected or faulty behaviour.
Not necessarily, since the volume control is digital, you could just, for example, select the controlled output with one encoder, and then control the volume with the other. In ADI-2 DAC, I think, there is actually just one DAC inside the box, and two output stages, which are being connected/disconnected through relays. That's why it's physically clicking when switching outputs, and that's why only one of them can be active at the same time. :)

As an example of one such device, my E-MU 1616m is fully digitally controlled (through software) and can have all of its whopping 16 outputs active at the same time and controlled individually. There's probably a separate DAC for each pair of channels. That thing is a beast, though, I don't need 90% of its functions, it lacks a good headphone amp, and it no longer works on modern Windows. (Official support ended with Vista, lol, and E-MU is now defunct :()
 
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KSTR

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- Even then, Foobar2000 WASAPI support is broken, I could get 16 and 24 bit tests to pass, but not 32. And other issues. As much as I like F2k, forget about it for WASAPI.
Foobars internal processing is 32bit floating point which has not enough mantissa bits to hold 32bit integers, that's why foobar cannot pass RME's 32bit Testfiles even if the driver (ASIO, WASAPI, whatever) accept 32bit integers. Even with all processing off and volume at 100%, one conversion to 32bit float and back always takes place.
Basically, a non-issue. 24bit integer is sure good enough for data passing to the RME.
 
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Foobars internal processing is 32bit floating point which has not enough mantissa bits to hold 32bit integers, that's why foobar cannot pass RME's 32bit Testfiles even if the driver (ASIO, WASAPI, whatever) accept 32bit integers. Even with all processing off and volume at 100%, one conversion to 32bit float and back always takes place.
Basically, a non-issue. 24bit integer is sure good enough for data passing to the RME.
Well, not exactly (pun intended :)), since 24 bit integers can have 8 significant decimal digits, and 32 bit (single precision) float only guarantees that integers with 6 or less significant digits will be preserved when converting to single precision and back. Please correct if I'm wrong!
 

KSTR

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You have to think in binary digits, not decimal ones. 32float has 24 bits of mantissa, 23 of which are stored, the MSB is always 1. And a sign bit, and 8 bits of binary exponent. By this the full 24bit integer resolution is preserved. Simple proof is that RME 24bit test files pass on players/editors that work with 32bit floats, like Foobar, Adobe Audition etc.
 

MC_RME

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3. One other thing that was not clear to me from all the reviews and product descriptions, is that the ADI-2 DAC can't use all of its outputs independently. It only toggles between them, either manually or automatically. Furthermore, the "phones" and "IEM" outputs are not separated -- they are both active at the same time and share volume control. This is not a huge problem for me personally, though something to keep in mind if you're considering this device and want to use all outputs independently and at the same time. :confused:
Apart from the single DAC design of this unit you might have missed this newer addition:

New option Mute Line – Toggle Plugged (Setup – Options – Device Mode). Having plugged-in Phones and IEM, switching via long press of the Volume knob now toggles between Line (rear), Phones, IEM, back to Line (rear) and so on.

Also (to make this clear again) you can use all three outputs at the same time, but with the same volume control and the same DSP FX. Phones and rear outputs can have different reference levels, though, which helps to adapt them and align volume between these outputs.
 
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