I had thought I had solved this problem when it was suggested I needed to get to this Roon screen:
However, the above looks like the output will be fed into an HT receiver - which will recognise the terms âLeftâ and âRightâ.
In my 3-way active system, I have:
- DAC #1 outputting to the subsâ plate amps
- DAC #2 outputting to the stereo amp driving the mids, and
- DAC #3 outputting to the stereo amp driving the tweeters.
I need delay applied to DACs #2 & #3 - yet this doesnât seem to match with the Roon screen, above?
Links for context follow.
Sorry if I put you on the wrong path in your previous thread here:
In this thread, you just asked for âsome delay to the mainsâ and I didnât realize that you are the same person with the strange setup of feeding a Roon zone group into 3 separate DACs. You mentioned it in passing in a later post in the thread but I missed this info. For anyone looking into this, take note of the older thread:
As I said there, I doubt that this is a good idea with Roon but you were convinced it is - but I have no further ideas here. Hopefully someone else does.
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Thanks for your input anyway, Sk. 
I now have all three DACs grouped together - so all seems good. All I need is for delay to apply to a DAC (or in my case, two).
IDK if this thread will help, but I recall @Graeme_Finlayson having an active multichannel setup.
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@Andrew_Redwood Iâve never tried running separate DACs in multi-channel. Itâs not the recommended route as thereâs no way to guarantee the DACs will stay in sync well enough to keep the timing across all three active channels. You have three DAC clocks that can drift out of sync.
The recommended route is to use a multi-channel DAC - thereâs only one clock so all channels stay in sync.
Iâve never played with timings in Roon either. I use Acourate to generate linear phase FIR convolution filters for each channel. Time alignment is done in the next step after individual driver linearisation.
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Well, I have finally (with remote help from my mate who initially set it up) got it all working correctly again - including applying delay to the DACs which feed my 2-way active mains.
Yes, many people have put forward the âmultiple DACs will just go out of syncâ issue. All I can say is ⌠people who come to listen to my system say âit sounds greatâ!
So it seems to me either a. that is a spurious concern ⌠or b. Topping E30s donât suffer from that problem ⌠or c. Roon somehow zeroises the drift - possibly by restarting the clocks at every track?
Roon doesnât control timing; the DAC does. However, in a grouped configuration only one DAC can do this, which can, and does, lead to synchronization issues.
So, @mjw after how many seconds/hours/days/weeks/months should such synchronisation issues become apparent?
Because, so far ⌠I have not been able to hear that anything is awry.
Roon RAAT adds samples to get the DACs back in sync when it decides they are too far out. So they donât drift over time.
As has been said Roon Labs donât consider this accurate enough for use within a zone, but fine between zones.
Of course YMMV.
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As @GregD said, the design goal is to be sufficient for multi room sync without echoes. From the specs:
- Tight playback synchronization suitable for multi-room listening. Thereâs a careful line to walk here. If we demand ultra-tight (1-10us) sync, it becomes impossible to implement the system on existing/unspecialized/heterogeneous hardware platforms. We shoot to be within 1ms (and under ideal circumstances often much better), which is more than adequate for multi-room listening.
From: https://help.roonlabs.com/portal/en/kb/articles/raat
So 1ms would be quite a lot if we consider the frequency spectrum of music. We donât know how much better the âmuch betterâ is under ideal circumstances, but chances are that itâs not negligible. Plus the clocks of three separate DACs, even the same model, wonât be 100% in sync either.
Considering the lengths designers go to for clock accuracy in DAC design, as well as minimizing phase shift in speaker design, I really donât know about this whole setup. And then thereâs the practical inconveniences of misusing Roonâs zone grouping.
After spending probably quite some money on active crossovers and separate amps, and I suppose on speakers, I really think you should bite the final bullet and get a proper DAC thatâs designed for this.
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Thanks, Sk and others.
Yes, I agree - at some stage I should get an 8-channel DAC (I donât think 6-channels DACs exist).
But as this would be a fair chunk of cash (for a reputable one) ⌠I shall wait until anomalies start appearing in what I hear.
BTW, I donât think Iâm âmisusingâ Roonâs zone grouping - just using it in a different way. 
I donât use Roon for different zones around the house - it serves my âlistening roomâ system only. (I do have speakers in 4 other rooms in the house - these are driven by a separate amp and a Niles spkr selector.)
In a way thatâs not covered by its technical design goals and constraints
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Thatâs kind od a how long is a piece of string question, and depends on the individual DACs. Hoever, if you read the forums you will find examples where zones do get out of sync.
Sure.
I can understand that theory says they should get out of sync.
All Iâm saying is that ⌠I am unable to hear any problems. Even though I leave my DACs on, 24x7.
I suspect timing issues have more to do with latency than clock drift. If itâs working for you, you may be fortunate, but at least nothing needs fixing now.
Thanks. Yes, I seem to have gotten past the weird problem I was having - and it now sounds as it should.
But I now understand how a multi-channel DAC works - so I will keep my eyes open for one. Unfortunately, 6 or 8 channels and RCA outputs, not XLR ⌠doesnât seem to be available, atm. 
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Maybe this?
or
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Thank you again, Sk.