Hi,
I found this thread as I am having issues with Cubase and my MR816x. I have posted here as I have had no luck elsewhere.
I also have no hardware option in the mixer list.
I could not get the Rev-X to work until I downloaded a Core Audio update, but it works now. Steinberg support did not help me find this? I discovered it myself - they told me I had to register with an authorisation code to get Rev-X working - support got it wrong, it does not use an authorisation code?!
I am not using Cubase 7 but I still have the issue using Cubase 5.5.3, to show that it is not related to Version 7 only with the missing hardware option in the mixer.
iMac late 2012
OSX 10.8.3