Spotted something that made me laugh (and had my eyelid twitching) when I was enjoying Rossini/Bartók comparisons last week:
I’d love to know whether or not dCS will standardise on the space between the volume figure and the units…
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What’s funny is that Vivaldi appears the same as Bartok. Rossini is the different one.
Ah, interesting!
And it seems that Rossini has it correct:
…though using a space with a few other example SI units looks odd to me:
1 m (weird)
1m (
)
1 g (weird)
1g ()
I had never heard mention of a “Bel” — despite it being pretty obvious that it existed 
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Exhuming this old thread as I couldn’t see the answer to this here, apologies if I missed it! I am using a Vivaldi stack with an Upsampler and DAC but no RS232 cable (the dealer forgot to pop it in, now on the way).
So how do Mosaic and Roon steer the volume in this scenario? No contact between Mosaic Control and the DAC, so is the attenuation applied in the Upsampler (and in the case of Mosaic does the regime change if the RS-232 cable is used)??
I am going to attempt to answer this without disassembling my RS232 connections.
I think the answer should lbecome clear to you when you get the cable.
Open the system control in Mosaic ( the “hamburger” menu top left corner). If I am correct ,when you open “Audio” the components shown will not include dCS Vivaldi DAC, only dCs Vivaldi Upsampler. Mosaic will be unable to find the DAC. This unit will appear in Mosaic when you get the RS232 installed.
If Mosaic cannot find the DAC then it cannot be used to control the DAC’s volume control. If the volume does alter then it must be taking place elsewhere. For the reason in my opening sentence I am not trying 
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Thanks @PAR, good to hear from you! Reading back throught the archives I understand the problems you have getting to the back of your rack! No problem, I strongly suspect the Upsampler deputizes for the DAC in the absence of an RS-232, just want someone who actually knows to confirm (@Phil?).
Hi Pete, Received my cable today and connected it up. It seems to be working inasmuch as I can now see the version information for the DAC in Mosaic, however the DAC still doesn’t show up as a device in “Device Selection”, even after switching both units off (i.e. at the back) and restarting them again. So I am still unable to set, for instance, the analog output level on the DAC from Mosaic. Looking at the Mosaic Manual doesn’t help as the example configuration consists only of a Rossini Player, so no real hint of the desired behaviour in a Vivaldi stack…
However presumably this is the intended behaviour?
Device Selection" appears when Mosaic app is connecting to Mosaic itself in the unit. When it connects to Vivaldi Upsampler then the usual “Services” screen appears. You will only see the DAC as an entity in the system control Audio and Device views. I would guess that you might see a choice in the “Device Selection” screen if there is a choice of dCS units with Mosaic connected to the same network.Those with , say, Vivaldi and Bartok may be able to confirm.
So it appears from what you say that all is well. I wonder if you have a preconceived mental image of how it functions which differs from reality? To set the DAC line output level you go to the control option ( hamburger menu) and choose “Audio”. Vivaldi Upampler is displayed at the top of the screen, Vivadli DAC follows. Each of the control attributes shows in black and white . The current choice is displayed in blue against this. There are no text options such as “next” or “up/down”. You just tap the blue option selected. For output voltage this action opens a new screen and the options for output voltage are displayed and may be selected.
This is what I am not seeing. There is no DAC under my Upsampler in the hamburger menu. My Bartók shows up (if connected) and my Upsampler but not my Vivaldi DAC. RS-232 Mode is set to “Text” on both units. Hmmm…
I cannot tell from your screenshot selection in that you can’t see the DAC as it normally does not feature in those views anyway.
You have to open the " Audio" selection in the first of these screens. Then you should see it. Let me know.
Thanks. This is precisely the same issue I had last year. I will PM you.
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Pete has been extremely helpful and we’ve managed to eliminate a couple of possible causes. However no closer to a solution. @Phil, I think we need the heavy artillery! I have lots of screenshots of Mosaic and the display on the unit I can share as needed.
Hi,
There is no volume control functionality in the Upsampler, only in the DAC.
There’s always a lot to mop up on Mondays so only just got here …
Right, if you’;re not getting access to the DAC controls from Mosaic then can you take photos of all the pages of information in the front panel Menu → Information → Status menus for both the Upsampler and DAC and get them to me at [email protected] and I can get it laid out in front of the R&D guys… oddly I was talking to one of our R&D directors about Pete’s issue this morning so annoying as it is from your end it’s quite timely from mine.
Thanks
Phil
Understood. So how, in the absence of an RS-232 cable (which I only connected today), do Mosaic and Roon control the volume when they can only “see” the Upsampler and there is no communication Upsampler ↔ DAC??
No worries at all, this is hardly a “production site down” situation. Everything appears to be working fine except I am unable to change the output voltage (and other DAC settings) remotely. Not exactly a showstopper!
Many thanks Phil, will do!
The Upsampler talks to the DAC (and vice-versa) via the RS232 cable AND the data frames that are part of the AES connection…
Haha! Cunning stuff! Thanks. 
I should have said we use a variant of the Qi charging standard to do wireless communication via the units lids and bases shouldn’t I?