Thanks for the answers! I'm not intending convolution so that sounds very encouraging, could be worth trying this, then :-)
Yeah I can accept that the start button issue may/will happen again if I go for win10, but that shouldn't matter as much on a dedicated music machine. Its when it happens to the laptop that I'm trying to work on that it gets annoying (there are other side effects too).
I realise that responsibility for this is an emotive issue, but as an end user its largely academic; the reality is that MS isn't fixing it and JRiver continues to trigger it so I have to deal with it either way. My entire OS isn't going to be changed in order to be more compatible with JRiver, but I like JRiver enough that I'd prefer not to drop it either - so thats why a cheap second machine looks like an answer.
Thanks for the suggestion of the compute sticks, they look like a good idea! The core M version will be too expensive for me (at least initially) but the atom versions are a fraction of the price so could be worthwhile. I have no TV or monitor to use with the stick though, so that will take a bit of thought. It may be that a built in 10" screen could make things easier and more flexible as a stand-alone player.
Thanks again
Kev