1 (edited by f1shb0n3 2021-09-05 23:10:48)

Topic: RME ADI-2 Pro FS as digital "preamp" success story and feature request

Recently added ADI-2 Pro FS in my system with great success getting a lot of unique benefits and wanted to share my experience. I use it in a way I've not seen mentioned in the forums and the manual does not explicitly show this configuration although I inferred from it that it would be possible.
Along the way I found some minor inconveniences that can be easily addressed with a firmware update and would also propose a major new feature I believe is possible to implement that's going to make the device even more valuable in similar use cases.

My system before ADI-2 Pro:

PC/Source ---> MiniDSP SHD ---(coax digital)---> DAC ---(XLR analog)---> amp ---> speakers
                             |
                              \---> subwoofers

It sounds great and all, but I wanted in addition to have:
    - Better volume knob
    - Headphone amplifier with PEQ
    - Single button switch between headphones and speakers
    - Dynamic Loudness - can't emphasize how important this is when listening to lower volumes and only RME has a proper configurable implementation of this!
    - Bass/Treble controls

I've used ADI-2 DAC before in the same configuration feeding its analog output to SHD's analog input that does analog to digital conversion(ADC), but this was not optimal as I was hearing audible degradation of the signal from SHD's ADC which also operates on attenuated signal. Feeding the source to ADI-2 Pro and connecting it digitally to SHD I got all the features and convenience I wanted and my system is now as perfect as it can be!

Here's the final picture of my system:

PC/Source ---> RME ADI-2 Pro ---(AES digital)---> MiniDSP SHD ---(coax digital)---> DAC ---(XLR analog)---> amp ---> speakers
                                    |                                                        |
                                     \---> headphones                               \---> subwoofers

Notes on ADI-2 Pro setup to achieve that for anyone doing the same:
    - Setup / Options / Device Mode:
            Basic Mode = "DAC"
            CC-Mode = "Stereo" (to change that disconnect USB temporarily)
            Dig. Out Source = "Main Out". Very important, as when it's Default the digital output is at full volume.
    - MiniDSP SHD's volume is set at 0db (max) and I don't ever change it, only using ADI-2 Pro to control volume.

What I miss in ADI-2 Pro vs ADI-2 DAC (feature requests):
    - Indicator on the screen for Loudness, Crossfeed and PEQ enabled. ADI-2 Pro shows two rows with Main Out 1/2 and Phones 3/4 with their volume, so I understand there isn't much screen real estate left to show it the same way as ADI-2 DAC. Still I believe you can shrink the text a bit and come up with some icons that indicate the important modifiers of the signal being on or off. Ideally this would be a new main screen view to keep it "backwards-compatible" for whoever likes it the way it is.
    - Ability to toggle switch between Phones 1/2, Phones 3/4 and Main 1/2 (digital or DAC). I like to have two pairs of headphones connected each with their own PEQ settings and such and would like to play only one of them at a time. To achieve that currently I need to mute and un-mute 1/2 and 3/4 manually which is cumbersome.

I think these features should be perfectly doable in software. My high expectations are that the Pro has everything that DAC has and more, not less and hope you would consider implementing them!

Thanks RME for creating such an awesome device, it has added much appreciated convenience in my setup and great improvement in my listening experience!
Special thanks to Matthias for his role in it and his helpful feedback on this and other forums!

2 (edited by f1shb0n3 2021-09-05 23:09:51)

Re: RME ADI-2 Pro FS as digital "preamp" success story and feature request

Now I will allow myself to dream a bit and request a new major feature that I believe is totally possible to do with the Pro with some major software work.
Essentially I want to use ADI-2 Pro's great DAC and multi-stage preamp in this current system replacing the Topping D90 DAC, but keep the MiniDSP processor in the signal path for it's 10 band PEQ and Dirac Live processing. It would be a new mode for ADI-2 Pro which can be called "DAC with external processor" that sends the main fully processed (Loudness, volume, PEQ, etc.) digital signal to coax digital output to an external processor (SHD in my case) and then takes coax digital input of the processed signal and sends it to the DAC and preamp for a clean analog output. Here's how it would look:

PC/Source (USB, optical or AES) ---> RME ADI-2 Pro ---(attenuated processed digital coax)---> Processor ---(coax digital)---> ADI-2 Pro ---(XLR analog)---> amplifier

I fully understand your engineers will find many good reasons why it's going to be complex to implement as it would break the typical "flow" of the device. Consider the amazing benefits it would provide to your customers though - being able to easily integrate an external digital crossover, PEQ with more bands including FIR filters, Dirac Live, etc. while keeping ADI-2 Pro at the heart of the system with its many awesome benefits.

3

Re: RME ADI-2 Pro FS as digital "preamp" success story and feature request

Wouldn't that require to have the current DSP path two times? Which would be impossible.

Regards
Matthias Carstens
RME

Re: RME ADI-2 Pro FS as digital "preamp" success story and feature request

"External processor" mode could be only one DSP applied at source and final signal sent only to DAC. The tricky part if it's even possible to implement would be matching the output level of the multi-stage preamp and headphone amp to the externally processed digital signal which might be additionally attenuated.

This feature will would open the device to many interesting use cases that might have relevance to your pro customers too. I know it's a long shot request, but having such a Swiss army knife of a device makes us users want it to do more and more smile
Here's a crazy even more generic feature request that could allow this to be configured by advanced customers:
Ability to set up custom modes or presets in a desktop app with fully configurable block diagram of how to route signal from inputs to outputs, where to apply DSP and attenuation etc. You kind of have all that set up "hardcoded" in software to do the different modes it has right now. Hey, if you open source the firmware or parts of it the community (inc. myself) will be interested to contribute many cool features you have not even thought of smile

I'd personally be happy to see first feature parity with ADI-2 DAC by having DSP info on display and 3-way switch between main out, headphone 1/2 and headphone 3/4. Hope you have this on the roadmap!

5 (edited by KaiS 2021-09-06 15:57:53)

Re: RME ADI-2 Pro FS as digital "preamp" success story and feature request

Have a look at manual page 42:
With the option “Digital Output Source” you can configure:

PC —> USB —> ADI digital out —> ( MiniDSDP ) —> ADI digital in —> ADI’s various analog outputs, with DSP processing and Volume Control:
Main —> speakers
PH 1/2 —> headphones 1 (select USB input)
PH 3/4 —> headphones 2

To switch headphones (and main) you have to plug and unplug them.

ADi-2 automatically switches individual DSP settings when it detects the headphones pluging action.
This is important for the Main <> HP1/2 change.

You can even use the “Settings” to store and recall different configurations.
If you do use PH 3/4 as primary headphones output this needs to be done occasionally only.


BTW: in the studio we call this “Insert”, a send and return path to plug in external processing, while keeping a device’s main I/O’s.

Re: RME ADI-2 Pro FS as digital "preamp" success story and feature request

Thanks, KaiS - the path you described works fine, but in my use case I need the DSP and volume to be applied first and the externally precessed signal to go to unmodified to DAC. This would allow the external processor to also do subwoofer crossover and volume to be controlled for them simultaneously with the DAC output of RME. It’s quite possible there are hardware limitations that prohibit that use case though and that’s totally fine. I still have a great system as is, I’m just greedy for some extra SINAD from the variable output stage and to cut out an external DAC component to save on cost smile

7 (edited by KaiS 2021-09-08 01:28:23)

Re: RME ADI-2 Pro FS as digital "preamp" success story and feature request

If you branch out from MiniDSP separately to main speakers and subwoofer, there is no other convenient way than do it post ADI-2 Pro.

Using a digital interconnect with 24 bit interfacing even on MiniDSP’s input, you can dial down the volume by about 40 dB and still are above CD resolution.
With good level matching it should be possible to have the “normal” listening level around -20 dBr.


A little less convenient, but using ADI-2 Pro’s superior DAC ‘s:

PC —> SPDIF—> MiniDSP,
MiniDSP main out —>ADI-2 AES in, Volume linked, main out —> MainSpkr
MiniDSP sub out —>ADI-2 SPDIFin, Volume linked, 3/4 out —> Sub

ADI-2 Pro’s mode can be “Digital Through”, manual page 41, or AD/DA converter, manual page 39.

PH 1/2 would still be usable for various headphones, but needs to bypass MiniDSP (e.g. by a 2nd digital connection PC—>ADI-2) and switching ADI-2’s setups.

Re: RME ADI-2 Pro FS as digital "preamp" success story and feature request

Currently using the first option you described feeding 32bit 96kHz to MiniDSP which has 32bit internal processing so there should be no digital volume distortion (if that's the correct term) that can happen with 24bit digital attenuation, assuming ADI-2 Pro sends 32bits out too. I don't really understand if the DAC after MiniDSP would underperform when fed -30dB to -20dB digital signal (vs a full-scale 0dB signal where DACs usually have best performance in terms of THD+N). In any case I'm sure it's all in the theoretical inaudible realm.

The second option you mention is neat, hadn't thought of that!

Re: RME ADI-2 Pro FS as digital "preamp" success story and feature request

There‘s no 32 bit through AES / SPDIF.
These are limited to 24 bit.

Still, 24 bit has a theoretical resolution of 144 dB, with dither even more.
More than enough.

The golden rule:
If you don’t hear noise you don’t have a noise problem.