Thank you MM, trackbeo and Geoff for your excellent considered responses.
I have read them carefully.
I’m agreeing with MM that actually it is probably best that I start with the simplest route and possibly explore more complicated options if I feel the urge.
So, the simplest route is to use AirPlay 2 to send from my iPhone or iPad wirelessly. I don’t have to use Apple Music alone for that of course, I actually keep some files on my iPhone in Vox player. That’s the free version of Vox player, but if I upgrade to being a paid user of Vox then I have very handy online space to keep my files and so it would work seamlessly with Vox player on my Mac. That would be much simpler than building a network with Roon.
As an aside I know that some people keep files in Apple Music and share across devices that way but I don’t like the way Apple Music deals with that. There are so many stories about the files being overwritten and then it is actually difficult to know with Apple Music if you are playing your own file or an online version.
Judging by the figures given by Trackbeo I think I’ll be totally fine with AirPlay 2. In my initial posting I wrote about Hi Res files, but actually, I’m not that into Hi Res, the main reason I want to be able to play my files is that they are just different versions from those offered up on the streaming services. 95% of my files are ripped from my CDs and of course they are 16bit 44.1khz. I have to say I find that “redbook” CD level to be totally fine. In my study I play those files on my Mac using Audirvana and I listen to them with my Meridian headphone amp and Sennheiser HD 800 S headphones and they sound absolutely superb! So, I don’t think I need a higher resolution capability than that really.
I do think that I will improve the quality of Wi Fi in my house. That is easy for me to do and it is an issue at present. I have the eero system however there is one unit connected to the my modem (virgin router in modem mode) and there are two other units in the house deployed wirelessly. If I finish the Cat 6A networking then I can connect those other eero units to that and I think that will improve Wi Fi reliability throughout the house. I think I shall get on with that and then have good Wi Fi in place and just try using the B & O 28s with AirPlay 2 from my iPad.
I like this as well because part of the plan is to keep as little tech stuff as possible in my living room. I really like the relaxed non-tech feel the room has. The B & O 28s will go very nicely in that room and not disturb its feel, but adding extra stuff, like an endpoint maybe with an LED screen or something will increase further the amount of tech. Okay, I know it could be hidden probably, but simpler maybe just to stick with AirPlay 2.