Sonos connect or DAC?

[nickc]

Yes, I know they're very different products! I'm still experimenting with streamed listening and have a very limited budget. In one living room at the moment I can only play streamed music (from a NAS with MinimServer) through the (modest but not rubbish, and hopefully to be upgraded one day) hi-fi system via a Sony BD player (connected by ethernet, not wi-fi) and an old Panasonic plasma tv. The Sony only has a digital (co-axial) audio-out and the amplifier only analogue in. It's annoying for various obvious reasons to involve the tv, so a solution, presumably, would be to have a DAC box linking the SonyBD output straight to the sound system. (A further advantage of course would be that we could use the sound system when watching Bluray movies etc.) But we've already got a Sonos Play 5 and a bridge serving an outlying studio room and I'd always imagined expanding the Sonos system, using Sonos Connect units attached to the separate hi-fi sytems in each of our two living rooms. I suppose I hope eventually to have both (Sonos and DAC), but I'm unsure which to prioritise and would appreciate advice re the likely relative sound quality in each case, viz. a) From NAS via Sonos wi-fi (with excellent signal due to good proximity) to Sonos Connect attached to the amplifier; or b) ethernet wired Sony BD player (BDP-S5200) connected by cables to the amplifier, via an under £300 DAC. Specifically, in terms of the different components, is there much to choose between the Sonos and the Sony boxes as renderers, for example? And what would the DAC bring to the set-up? What sort of DAC can you get for under £300? Any recommendations?