How to set up RME Digiface USB for dual SPDIF out?

[mike7877]

I have 2x Topping D90 III Sabre DACs and a Digiface USB which I plan to use together to drive my 2x LA90 Discrete amplifiers, one for tweeters, the other: woofers.


Fortunately I should be able to use the DACs in phase because they have two modes of operation when it comes to S/PDIF: Quality and Compatibility. In looking through the ESS datasheet, I believe Topping's compatibility mode uses the S/PDIF clock, and quality mode is re-clocking. Quality mode is probably best 99% of the time. But not this time lol.

Anyway, I've tested the DACs being fed the same optical signal, and reliably checked their phase. Things should be good to go as long as the digital inputs are sync'd.

RME's Digiface definitely outputs both S/PDIF and ADAT properly, I'm just.. stuck.

I can't get the Digiface to make the two devices look like one for software. I think I have to do some internal routing from the outputs that do show up in software, to the S/PDIF outputs. But I can't find anything on how to do this...

Is anyone experienced with RME's TotalMix FX?

 

[Redacted]

Sounds like a convoluted way to implement a bass/treble crossover.
It's not easy to synchronize separate digital signals without a master clock, but maybe I'm not understanding your kit and intention!

 

[john61ct]

Is the signal source a PC or RPi as Player via USB? in which case the Digiface is Master for clocking?

Or TOSlink input?

What OSs are involved?

What is the DSP unit handling the filtering / crossovers?

 

[mike7877]

Is the signal source a PC or RPi as Player via USB? in which case the Digiface is Master for clocking?

Or TOSlink input?

What OSs are involved?

What is the DSP unit handling the filtering / crossovers?

Sorry about the delay, I hope you're still able to help

Basically the PC (Windows 11) will be the DSP, and the output from the DSP program needs to be able to send to two separate devices - the Digiface USB has 4x optical outs, and I will have two of them set to TOSlink.

The clock of the two optical outs is sync'd in the Digiface, and two identical DACs are being used, configured to use the optical clock (no reclocking). All other settings are identical (filter etc.) so the latency should be close enough to identical. It's not ideal, but it's what I have.

I'm looking for how to get DSP Crossover software output to the two optical outs on the Digiface. The crossover software seems to see each optical out as a separate audio device, so I'm thinking some internal routing needs to be done so I can send the outputs to what look like the same device on the Digiface, to the outputs that, at default configuration, appear as different devices.
I've done some simple routing before with my Babyface Pro, but I have no experience past setting up for that one project, and the Digiface seems more complex

 

[mike7877]

Sounds like a convoluted way to implement a bass/treble crossover.
It's not easy to synchronize separate digital signals without a master clock, but maybe I'm not understanding your kit and intention!

Yes, it is... My speakers are ATC SCM20 Pro PSL Mk2. They are the passive version of a studio monitor. The reason I went passive was, at the time, I had an amazing amplifier - a 140WPC Class A - over 2kW of transistor per channel, a >1000VA toroid, >120,000uF bulk caps + >30k uF more for good measure...
Its bass? Legendary. Clarity? Pretty good!!!

I had to go and short it out and then give it to someone who said he'd fix it and just had it hang around for almost 2 years in his shop so I just stopped calling about it...

So the 140WPC Class A was into 8 ohms, 4 ohms that doubled, 2 ohms that doubled again. 1 ohm actually doubled again, but you could only drive one channel at a time because fuses lol.

Anyway, when Topping's LA90 Discrete came out, I went for it. And when I found out how powerful it is bridged (basically 4x), I got another. So I've been using that and the SCM20 Pro PSL Mk2s (8 ohm woofer, lowest AC resistance slightly below 6 ohms I believe). The LA90 Discrete does (coincidentally) 280W into 4 ohms (and so, at least 140W into 8 as well), matching the power of the previous amplifier, and surpassing its clarity. The bass seems a little lacking comparatively, but that could just be my sentiment lol.

So since I don't need all that power most of the time and I'd like to focus on high fidelity at lower volumes, I decided to un-bridge the amps into a stereo pair, to separately drive the woofer and tweeter of the (2-way) monitors.

I needed a DAC, and I liked the sound of the DAC I already had (the D90 III Sabre), and since I knew the datasheet of its heart (ESS ES9039MPro), I decided I wanted to use two of them!

I have tested them for phase, and they're in phase when the optical signal is sync'd (I used a splitter so the input signal was the same - I still haven't figured out how to get the output to come out the optical ports as needed.

 

[john61ct]

You did not answer all the relevant questions, and now I have more.

When you say S/PDIF you mean TOSlink?

4 channels total needed?

Why not just get a single USB interface with multichannel integrated DAC ports built in?

But yes the RME acts as master clock, dunno those DACs but set to slave mode should stay in sync via signal input.

Linux and Mac have plumbing to create an "aggregate" device, but if Windows check out @dualazmak use of VB Audio Matrix for ASIO routing

I would think your DAW / mixer / DSP software would just let you direct to the RME-presented channels directly though.

 

[phofman]

IIUC all you want is make the Digiface output first two channels to one toslink, and the next two channels to another toslink. So Digiface would present 4+ channels interface over USB to the PC. Then the DSP running on your PC would route the DSP'd streams to the respective channels of the USB interface. If the interface cannot be pushed to support only 4 playback channels (may it would report 8 channels only), then the remaining unused channels would be fetched zero/muted signal. IMO every decent DSP software should be able to do that. And IIUC that Digiface interface is versatile and routing the channels from the USB channels group to the two 2ch toslinks should be a matter of configuring the internal routing with the Digiface control software. Does not sound complicated.

 

[dualazmak]

...., but if Windows check out @dualazmak use of VB Audio Matrix for ASIO routing

Am I being called?
OK, if OP @mike7877 is interested in "my use case" of VB-Audio MATRIX as system-wide ASIO/VASIO/VAIO routing center, please visit my posts #931 and #1,022 on my project thread.

....
...., And IIUC that Digiface interface is versatile and routing the channels from the USB channels group to the two 2ch toslinks should be a matter of configuring the internal routing with the Digiface control software. Does not sound complicated.

Even though not directly related to RME Digiface, as I have shared here #842 on my project thread, two or three RME Fireface UFX III can be fully synchronized—either via word clock or by using AutoSync and feeding synchronized signals—which is clearly described in user manual of Fireface UFX III DAC/ADC .

 

[john61ct]

Am I being called?

No need to ask, that's what that string @dualazmak means

> Fireface UFX III DAC/ADC

94ch per interface should be more than enough for ?any recreational home listening use case, at $3k each why would you need multiple boxen? Are you mastering professionally , like orchestras?