Response from Denon:
Hi Andrew,
Thank you for your email. Please accept my sincerest apologies for the delay in correspondence.
We have been looking into this further on our side; trying to get access to an X1850 to test so we can confirm the below for you.
In summary, I can confirm that there is an error in the user manual. It has never been possible to remove the mics from the record output.
In terms of the 3 functions you require, the X1850 will not be able to provide all 3 natively. The way in which you’re currently using the mixer (i.e. Digital out to record OBS and Booth to record mix) is really the best way to do what you’re trying to, within the limitations of the mixers functionality. I understand you do not have another variable output available to you in this configuration.
In order to achieve the functionality you want; we would need to introduce another mixer/interface that has individual gain controls; which would allow us to split the signals and control the gains separately.
I hope this helps.
Should you have any further questions, concerns or require any additional information, please let me know.
Kind Regards, Billy Waller European Service Manager inMusic Europe Ltd