I consider to buy a second hand A9 if I can find a MK2, as I would use the multiroom feature. It seems sellers usually do not know whether they have the MK1 or MK2 version. I also found it difficult to find information about the differences when I searched Google and this forum.
Is there an easy way I can distinguish between the two by asking sellers for known functionality, ports or labels on the hardware? For example if only MK2 features Spotify or have a new input port?