Toslink VS coax VS other forms of Digital transfer

I am new to this forum and relatively new to digital audio in its present forms… My question, is there a "better way" from a technical or sonic view to connect devices to my new DAC?  

I have a Sonos connect unit which I use as a tuner and Tidal source as well as a few music playlists. It has an optical output, coax and the usual RCA single ended… I am auditioning an AQ power cable that has improved the sound a bit..

Sonos makes for  a lot of access and convenience however, I have never found the sound quality to be satisfying… I am told that going into the DAC optically will improve on that to a point… Bluesound is supportive of higher res files and I am sure there are other units that may be better yet…  Any thoughts?
Thx Cj
I love Sonos, but not for HiFi.  I have a couple of Sonos products in my home and I use them for in-ceiling speakers, outdoor, and other locations where music is just for background.

As for streaming Tidal to a DAC, I recommend doing that with a device that supports full res files, and doesn't limit you in any significant way.  Depending on the capabilities of your DAC, you may be able to go directly in with an ethernet cable, which would be ideal, as that would indicate the DAC has an on board player, and just needs to be fed the fully digital packets.  This is not the norm however.

I think the Bluesound Node option is a great one.  Not particularly expensive, handles high res files.  The connection is limited to Touslink and coaxial.  I would go coaxial.  From what I understand, Toslink is not great in the jitter department.

For a higher cost, AURALiC makes a streamer called Aries LE that rivals the blue sound, and it has proper HiFi grade digital outputs, such as USB and AES/EBU.

What DAC did you buy?

Toslinik vs Coax.  It is a system thing.  Coax, because of faster transitions is less sensitive to system noise, but have some sensitivity to ambient noise and reflections within the cable (use <8" or >1.5m cable), as well as ground loops.  Toslink does not create ground loops and is immune to ambient electrical noise, but because of slow transitions is sensitive to system noise.  The best is to try both.

Thanks so much for the clarity… I am primarily a CD guy…

I recently purchased an Audio Research Ref CD9…  I know it has no SACD but neither do I…

This is the deep end of the pool for a CD player and DAC to be sure… and far over my projected budget too… but…  

OMG!!!…   It has a totally seductive and emotive sound quality… amazing detail and more depth than I have never heard from a CD player… reminds me of the ultra clean yet extremely musical sound of an analog studio master…  very mesmerizing for me, I've only had it a few days and I am stunned by how my old CD's that seemed to have been poorly mixed come alive and the ones I thought were well made are astounding! …

Geez… I am a long retired AV system designer and rarely am I so impressed and yes, seduced, by a new piece of gear… 

I am also experimenting with various cables like the Shunyata research power cables, another new world for me… I ignored the AC issue for years… for me no hum or noise, no problem… I was wrong.   

I like buying American products and love supporting home grown, hands on, companies like ARC and Shunyata when budget allows… any thoughts regarding digital sources are also appreciated.

I understand internals of the ARC Ref 9 to be similar to that of the ARC DAC 8 supporting CD, RCA, USB, AES and TOS… I am not decided on which inputs are best used for what yet, so that is my current quest… still perusing the the owners manual.