On my system it looks like the Steinberg Audio plan is almost the same as the high performance plan, but some people have said it's like the balanced plan. On my system, it doesn't turn off any drives, not the monitor, nothing. In fact, while I don't know how this is supposed to work, perhaps it sets itself depending on how your system is set. That's the only thing I can guess . It would be nice if Steinberg could step in and explain this. The knowledge base is totally useless as it's so difficult to navigate the results. I just give up.
It does seem to be causing problems on my system since the 7.5 update as I'm now getting BSOD crashes that only appear when using this power plan. Again, this may be dependent on your system. My overall conclusion, and I'm definitely not an IT guy, is to turn it off.
As for not seeing it under your plan options, you only see it if you enable it within Cubase. If disabled, you won't have it as an option in the control panel.