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Measurements of RME ADI-2 DAC and Headphone Amp

Music1969

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According to the manual of the ADI-2 PRO fs (not the DAC, but I assume they are very similar in this respect) no resampling, but limitations due to available DSP power: no Bass, Treble and Loudness, and you have the choice between either EQ ((1 x stereo) or crossfeed. You can download the manual and check yourself. It is very informative.
Hi

Yes I quoted manual above (see my post above).

But I’m not clear if incoming PCM768kHz is resampled to a different rate for EQ and digital volume control on headphones output
 

KSTR

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But I’m not clear if incoming PCM768kHz is resampled to a different rate for EQ and digital volume control on headphones output
No, no "hidden" resampling whatsoever is applied. There isn't even software for that in the Adi-2 Pro and DAC.
The only resampling that may take place, for the Pro, is in a hardware chip on some of the digital inputs, but only if the user explicitely tells the device to do so (for specific applications, when unsync'd digital inputs have to be used).
 

MC_RME

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Downsampling would be such a big limitation of the unit's capabilities - don't you think that would be mentioned clearly if so? Also there would be no reason anymore to limit the available DSP features.
 

Music1969

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don't you think that would be mentioned clearly if so?

Thanks!

So for digital volume control done with headphone output, when fed 32bit PCM768KHZ , then it is ‘converted’ to 42 bit (TotalMix tech) but stays at same sample rate of PCM768KHZ ?
 

th0m

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Is anyone using Steam with the ADI-2 (with the default Windows driver)? Suddenly can't get any sound in any games anymore since I changed DAC. All other sounds in Windows works perfectly.
 

ShiZo

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Never had an issue with steam and my rme dac.
 

MC_RME

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Hi @MC_RME
If I need to ground the ADI-2 DAC due to ground loop hum (headphones output) what are your recommended methods?
Grounding the digital coax input is fine? Or is that input isolated?

That's fine, it is not isolated. Any ground connection will work, also RCA and XLR (pin 1).
 

Seige

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Hi everyone!

After some tinkering with the unit I realized that I cannot select 32 bit in the "Sound Control Panel" of Win10. It is limited to 24 bit, independent of the selected frequency. The Madi driver is installed. I tried to google it and also had a look at the the manual, but to no avail. Am I missing something very obvious here?

Could this be caused by the Babyface Pro that is also installed at the same machine?

TBC: I am not talking about ASIO and using a 32 bit audio file, but the option to set 32 bit within WDM.

Thanks,
Seige
 

ShiZo

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I also can only set it to 24 bit. I always assumed that is as intended.
 

Gus141

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@MC_RME or anyone else who has some insight into this question.

Is there any difference (besides how the volume is displayed) when configuring the Phones output between these two cases (they sound at the same loudness/SPL):

  1. Hi-Power=Off + Auto-Ref=On (but using a volume range that results in Lo-Power mode, and never activates Hi-Power mode). My average listening volume is -35 dBr.
Versus
  1. Hi-Power=Off + Auto-Ref=Off; so forcing Lo-Power mode. Average listening volume becomes -20 dB.

Both result in “Lo-Power” being displayed on the Details page for my volume ranges using efficient headphones. Hi-Power mode is never on.

There are different volume scales between those two cases (dB vs dBr) and when auto ref is on there is an adjustment of -15dBr on the volume indicator.

So, in essence I’m asking if there are any differences in noise, distortion or amplification between:
— Auto-Ref:On/Lo-Power mode (with volume set -15dBr lower than the next case below) and
— Auto-Ref:OFF/Lo-Power mode

because they sound the same loudness?
 

vitalii427

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@MC_RME or anyone else who has some insight into this question.

Is there any difference (besides how the volume is displayed) when configuring the Phones output between these two cases (they sound at the same loudness/SPL):

  1. Hi-Power=Off + Auto-Ref=On (but using a volume range that results in Lo-Power mode, and never activates Hi-Power mode). My average listening volume is -35 dBr.
Versus
  1. Hi-Power=Off + Auto-Ref=Off; so forcing Lo-Power mode. Average listening volume becomes -20 dB.

Both result in “Lo-Power” being displayed on the Details page for my volume ranges using efficient headphones. Hi-Power mode is never on.

There are different volume scales between those two cases (dB vs dBr) and when auto ref is on there is an adjustment of -15dBr on the volume indicator.

So, in essence I’m asking if there are any differences in noise, distortion or amplification between:
— Auto-Ref:On/Lo-Power mode (with volume set -15dBr lower than the next case below) and
— Auto-Ref:OFF/Lo-Power mode

because they sound the same loudness?
I bet both cases works the same.
 

VintageFlanker

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@MC_RME or anyone else who has some insight into this question.

Is there any difference (besides how the volume is displayed) when configuring the Phones output between these two cases (they sound at the same loudness/SPL):

  1. Hi-Power=Off + Auto-Ref=On (but using a volume range that results in Lo-Power mode, and never activates Hi-Power mode). My average listening volume is -35 dBr.
Versus
  1. Hi-Power=Off + Auto-Ref=Off; so forcing Lo-Power mode. Average listening volume becomes -20 dB.

Both result in “Lo-Power” being displayed on the Details page for my volume ranges using efficient headphones. Hi-Power mode is never on.

There are different volume scales between those two cases (dB vs dBr) and when auto ref is on there is an adjustment of -15dBr on the volume indicator.

So, in essence I’m asking if there are any differences in noise, distortion or amplification between:
— Auto-Ref:On/Lo-Power mode (with volume set -15dBr lower than the next case below) and
— Auto-Ref:OFF/Lo-Power mode

because they sound the same loudness?
To my knowledge, the Auto Ref Level is only active with the line out, not with the headphones amp.
 

KSTR

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So, in essence I’m asking if there are any differences in noise, distortion or amplification between:
— Auto-Ref:On/Lo-Power mode (with volume set -15dBr lower than the next case below) and
— Auto-Ref:OFF/Lo-Power mode

because they sound the same loudness?
Technically, in the actual signal flow, both are exactly equivalent. Only the display of the volume setting changes according to the available headroom. When the signal demands it, auto-ref then switches to the higher gain mode so that the output level can be reached, physically. With auto-ref off, there is no additional headroom to consider so the display reads 15dB higher dBr values for the same physical output level. That's what the "r" in dBr stands for, reference to the maximum achievable output for the given setting.
 

KSTR

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To my knowledge, the Auto Ref Level is only active with the line out, not with the headphones amp.
There are two sets of auto-ref level switchings, one for the line out in 6dB steps and one for the phones output with only two gain steps. Only when both are demanded to auto-ref at the same time there is a conflict.

Manual, section 19.6 (and a snippet before) says (my remarks in [ ] brackets):

Notes on Auto Ref Level: This technique includes switching of hardware elements (like when doing it manually) and is therefore not free of click noise. To prevent distortion the threshold for a Ref Level change takes EQ gains into account. Auto Ref on the Phones output will be inactive when Line Out and Phones out are set to work simultaneously, and Auto Ref is enabled on the Line out.

19.6 Using more than one Output
If SETUP – Options – Phones / DSD – Mute Line is set to OFF, all three outputs will work simultaneously. The Line out specifies all settings. Its EQ, Bass / Treble, Loudness etc can be heard on Phones and IEM output. Since the device only has one DA converter, it naturally can not output three different digitally processed stereo signals.


The Line volume setting affects all at the same time as well. By manually selecting Hi- and Lo-Power on the Phones output, it can be brought to a suitable base level.

If Auto Ref Level is active on Line Out, there will be jumps in level when the Ref Level is exceeded or below on the Phones output. This is not a mistake - there are not [four] hardware levels in steps of 6 dB on the phones out [rather only two settings, low and high], so you can hear the volume changes of the DSP from the Line out without the Line Out Ref Level compensation. To avoid this do not use Auto Ref Level in such a multi-output application.

If Auto Ref Level is active on Line Out and Phones, the feature will be disabled on Phones. For a similar reason - otherwise there is a very unpleasant increase in volume of 15 dB on the Phones output when switching from Lo to Hi Power. When using both headphone outputs, the output specifies the settings that will be used (plugged in) first. The device also remembers this when switched off and on again."
 
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