Hello
I do not use Room EQ nor ARC-USB so better wait a response from RME Staff or users more advanced than me sharing its knowledge to confirm that I’m not wrong …
concorde2 wrote:Can I upload these presets to the UCX II itself?
You cannot upload those standalone Room EQ presets directly to the UCX II but you can save the presets via Snapsot in TotalMix and after save the current state of TotalMix on any of the 6 physically Setups available and loadable from UCX II via stand-alone (without computer/TotalMix). All the above steps must be do it via TotalMix because Room EQ is a feature exclusive of.
Can I switch between these presets using only the UCX II?
Theoretically yes using the SETUP/REV front encoder of the UCX II following the path Options→Load/Store all Settings and selecting and loading one of the 6 physically Setups of the UCX II where you saved the current state of TotalMix before.
Would the ARC USB Remote Control make this any simpler?
From what I've read here, yes, it is possible to easily load saved Snapsots in TotalMix but I can't confirm if it can be done in stand-alone operation (offline computer) or if it must be done exclusively with ARC + UCX II + TotalMix online. More help here please ...
Could I therefore switch between Room EQ presets on the unit or with remote, while using Linux - as the presets would be on the unit itself?
There is no Linux official support from RME, no proprietary driver nor TotalMix so no Room EQ. If your main/host OS will be Linux you can create a Windows VM and via USB passthrogh sync and save all TotalMix settings/state to the UCX II but it is tedious and an archaic process because to support UCX II under Linux the CC Mode (Class Compliant) is essential and for activate it the computer must be off/sleeping, or if you don’t want poweroff/sleep your computer the UCX II must be off , disconnect the USB cable, turn on device and change to CC Mode, turn off again device, reconnect the USB cable and turn on again device 
… unfortunately there is no way to change to CC Mode while computer and device are online … except if some day RME change this.
BUT if you have correctly saved all the states and configurations via TotalMix/Windows in the 6 physical UCX II Setups you’ll be able to load them using the SETUP/REV front encoder even though the device is in CC Mode (Linux).
Would there be any way to simultaneously switch between the presets of the 3-band PEQ on the unit?
No computer/TotalMix is needed to do this. All PEQs can be set, store and load in stand-alone operation using the CHAN/MIX and SETUP/REV front encoders of the UCX II.
EDIT 2024/11/06:
tonpalt wrote:concorde2 wrote:Can I upload these presets to the UCX II itself?
You cannot upload those standalone Room EQ presets directly to the UCX II but you can save the presets via Snapsot in TotalMix and after save the current state of TotalMix on any of the 6 physically Setups available and loadable from UCX II via stand-alone (without computer/TotalMix). All the above steps must be do it via TotalMix because Room EQ is a feature exclusive of.
I was wrong, Room EQ for UCX II is a feature also in DSP (Firmware) and not only in TotalMix. Therefore it is posible set, store and load custom presets without computer/TotalMix on device itself via stand-alone operation. To keep in mind that ANY change on UCX II cannot be stored individually, the 6 physically Setups are for store the complete current state of device
UCX II FW106/34/104 v1.253 TM1.97 - PC Win11 23H2 / Fedora WS 41 - Reaper 7.27
