Roon & Apple aggregated USB devices

[grizaudio (Stephen)]

Hi,

I’m looking to Apple power users for some advice.

I currently run an active setup. Signal path is:
Intel NUC Roon Rock> USB > Raspberry Pi4b > USB > Intona 7055-B > USB > Motu Mk5 Ultralite > Active 2 way speaker setup

All Crossovers are done using Roon convolution.

My goal is to use multiple R2R dac’s in place of the Motu MK5 Ultralite.
I have been researching Apple USB device aggregation as a potential solution (One of a few).

If I use as an example 2x USB R2R Dac’s, can Apple OS present these aggregated devices to Roon as a single output device?

I also have concerns relating to clocking variance;
Can apple monitor and control this, is this what the Drift function is for, or would an external 10mhz clock be a safer bet?

Thanks

[Traian_Boldea]

Ițm a newbie so I do not understand 100% what are you trying to do. I am reading now for the first time about aggregation. Interesting.

I have 2 usb dacs (200m and zen dac v2). if you think that I can try something to see how it is going let me know.

[mitr (Kal Rubinson)]

@grizaudio

My goal is to use multiple R2R dac’s in place of the Motu MK5 Ultralite.
I have been researching Apple USB device aggregation as a potential solution (One of a few).

I have done this with several different DACs and it works well. Better with clock links.

[GregD (Greg Dowling)]

I believe you can aggregate the two devices. You should sync the two clocks to avoid drift.

But given the choice I would avoid it. The sync between the devices is super important in your application, and you are depending on apple’s software to do this

I think a better solution would be to use a 4 output DAC that will do routing / DSP. I’m pretty sure an RME ADI-2 pro will (although one of the stereo DACs is unbalanced)l (or even better the new ADI-2/4 pro - which has 4 balanced outputs).

Then the sync issues will be taken care of in hardware /firmware.

[grizaudio (Stephen)]

Thanks Greg,

The goal is to explore R2R, and move away from Delta Sigma solutions, which are obviously the easier path.

I could easily stick with my Motu MK5 UL, or move to any number of pro interfaces , Okto Dac8 Pro, Topping DM7 etc.

But these solutions are sideways steps, and mirror my current setup.

[grizaudio (Stephen)]

Thanks for this feedback, great to know.
I feel the clock link is the best method for insuring timing.

[GregD (Greg Dowling)]

So there are pro audio devices that support multiple digital outputs, although off the top of my head I can’t think of a single box solution.

You can find audio interfaces that provide ADAT or MADI outputs

ADAT provides 16/8/4 outputs in a single fiber at 48/96/192 kHz

MADI provides 64/32/16 outputs at 48/96/192

In the RME world, which I know best, you’d need an interface with ADAT or MADI outputs and then a digital router to split this to multiple AES / SPDIF stereo outputs.

Do you also need dsp to do the crossover between the low/hi drivers?

This is going to be expensive - so hopefully there’s a better / cheaper solution.

One other idea is that you can buy AES splitters - which split a single AES stereo signal into multiple. They are often passive with transformers - so won’t effect the timing. Do your DACs have AES inputs?

Obvious you can’t do any dsp/ crossover processing with this option.

[GregD (Greg Dowling)]

Seems you can buy SPDIF coax splitters cheaply too.

[GregD (Greg Dowling)]

Re-reading your post you’re using room convolution for the crossover dsp - do the splitter idea won’t work.

So despite my reservations - aggregating the interfaces seems like the best idea!

[grizaudio (Stephen)]

Hi Greg,

Thanks I’m all over this, I just don’t have an Apple PC to test the scenario - which is why I asked the community.

Another direction is using something like this, with DAC’s of my choice:

Digiface USB | portable USB ADAT Audio Interface - rme-usa.com

[GregD (Greg Dowling)]

The digiface series is much respected.

But I don’t know if you can connect its outputs to your DACs.

Some RME devices allow you to switch the pro multi channel ADAT to the consumer TOSLINK / SPDIF. So you could check the manual.

Otherwise you’re going to need a digital router as well.

[grizaudio (Stephen)]

Yep, the device allows configurable outputs. All good there.

[GregD (Greg Dowling)]

So that looks good.

Your other issue is that roon won’t be expecting to see that many outputs - and will likely just output to the first 2/4/5.

RME’s total mix software should let you re-route as needed.

[grizaudio (Stephen)]

Greg,

Roon allows routing up to 8 channels, via USB.
The process is no different to my Motu which provides 10 outputs, and 8 can be mapped.

Roon controls all channel routing using IIR procedural/mix or if Convolution FIR is used, channel mapping/assignment is done in the filter using the .cfg file.

Lets leave it there.

[Traian_Boldea]

Lovely discussion. I’m not as advanced as you are. You just tell me to shut up

I do have a hip dac, a zen dac, a 200m and tried out the aggregated. One weird think is that I cannot aggregate the first two, both devices on and os sees only one iFi. So I pulled out 200M, mow it sees 2 devies and I can connect them. I see the aggregate as a separate device in roon. If I can do more just tell me but now I have to run to work