Yes, absolutely, it can be plug and play after setup. This was exactly how I used my A8 for many years. I once made a 7.0 PRIR, was blown away about it's performance and used it from that day on more or less as you plan to do so: just power it on and use it - as simple as that (a single PRIR and a single HPEQ for all sources - be it music (stereo) or movies).
After setup (eg: making a PRIR of a good pair of speakers and use them as front, center, rear, side, high etc. speakers during PRIR creation - and create a HPEQ), load the PRIR and HPEQ into a preset and forget about all the settings.
From that point in time, the A16 will work exactly as a copy of a real speaker system (means: sound played through the A16 and your headphone will exactly sound as if you would have installed all those speakers in the room you made the PRIR).
Eg: Create a 9.1.6 system (with virtual 16 speakers) - whatever signal you will feed into the A16, it will behave as if you would have 16 real loudspeakers:
- play a stereo source: just the virtual left and right speakers will play music - other virtual speakers will be on mute
- play a Dolby 5.1 source: just virtual front, center and surrounds will play the signal - other virtual speakers will be on mute
In short: as if you would have all those virtual speakers as real speakers. If you have a real 9.1.6 system installed and play a stereo source, just the front speakers will play music as well.
This is true as long as you do not switch on any upmixer of course - exactly as a real speaker system behaves. Complexity in the real world (after a correct setup has been done): near zero - just switch it on and enjoy.
If however (and this forum is mostly about that - and what the best working options are at the moment) you plan to improve the virtual system, get all you can out of the Realiser, create a virtual system that sounds even better then a real system ever can - than complexity will be higher (in the 'create a perfect PRIR and setup' phase). The A16 is an incredible piece of equipment already today and gets better with every new firmware. I'm not aware of any single product on the market which allows you doing things the A16 can do already today.
As an example: I made a PRIR of a good pair of speakers (incl. amplifiers) - this stereo pair had a cost of approx. 50k USD. I made a virtual copy of it as 7.0 system and are enjoining this over headphones since then (you would have to spend 175k USD just in speakers and amplifiers in the real world to create a similar experience - but would have to deal with an unhappy wife about the clutter, neighbours about the noise etc. etc) - with the A16: problems solved - and it costs less than 5%