Separate DAC or continue using the Oppo UDP-205

Nobody here has mentioned that Oppo is compatible with Roon. In other words you could do without that Sonos altogether. Roon running on your computer can manage your music collection, streaming etc and you could simply use the Oppo as a Roon endpoint (playback device). 

Regarding the Oppo itself it looks good on paper, good DAC chips, great SNR, very detailed but it fails where all but the most expensive DACs succeed: tonal balance. However, in your case, pairing it with valves probably compensates to a certain extent for the lean, mean, colourless sound signature of the Oppo. 

I would upgrade the switched mode power supply in the Oppo - it makes a difference (the sound becomes a little bit more refined / rounded and there is more meat on the bones so to speak). Clones Audio and Oppomod do good ones and all you need to replace it is a screwdriver and a bit of courage. 

Then get Roon. The Oppo is quite sensitive to trash in the mains so just removing the Sonos from your mains ring will give you a small boost in sound / video quality.  

Keep it simple. The whole point of it all is to enjoy the music and you do. So why fix something that doesn't need fixing? Just make the most out of what you've got. 

+1 to anwar.

A friend brought his laptop over to hear some live recordings he made and to listen to a few songs in his hard drive that I had on cd: that experience totally blew my mind, but Im too old to abandon 3-400 cds
You’re not likely going to like my answer, but here it goes

My dac/pre is a ~ 4 year old model Audio Alchemy DDP-1 dac/pre with PS-5 outboard power supply. I assumed it was a vg dac, and the resultant music sounded quite good, but, like you, Im thinking ’new dac’, however, I upgraded my amp to a EVS 1200 from Ric Schultz/TweakAudio. It took about 80 hours break in before the spooky magic started happening. I now have ~ 100 hours on it.

When the redbook CD recording is good the musicians are in the room comparable to when I had an all tube system; Lector pre and cd player, Rogue M150s with cryoed tubes run fully balanced (had to special  order the Lectors to get fully balanced).

Best of all, it’s only $2200 for 600wpc idle wattage is a low 57watts meaning I can leave it on 24/7, although it has standby toggles which reduce wattage to 1-2 watts, which one would employ if they turn off their tube pre between sessions.

 I think its great that we can post a question and get so many different opinions, but while I read all these answers I have to make a decision.

 So, I got another Hard drive. I formatted it to work directly with the Oppo, eliminating the Sonos. Now I can just switch the Oppo from Optical to USB and compare the sound. If I hear a difference I will let all of you know, I am sure I will.
Then I can see what direction I can go. I really thank all of you for your suggestions, and of course let you know what way I go. As I said in the beginning, I was happy with the sound, but always like to tinker. Especially if it doesn't cost a lot money.

 By the way, I would never sell the Oppo, It does an incredible job with DVD'S.

Andy

tweak1,
Are you saying that your friend's hard drive version of the same recordings on CD sound superior to the CD?  In what way?

The OPPO 205 functions - via USB and wifi - as a full Roon endpoint (rendering and decoding). wifi works flawlessly, if you have a good home wifi system (Linksys Velop, Google mesh, ...). If you replace the SONOS with a Roon Nucleus (or download Roon on a MacBook), you should be able to consolidate all your sources (stored and streamed) - except Spotify - on one very powerful streamer platform (Roon) with excellent user interface and use the OPPO as DAC.
If desired, Roon supports multi-room functionality as well.
This configuration supports hi rez and MQA as well.
I have compared the OPPO extensively to a number of other DACs (Mytek, Cambridge 840, DSpeaker X4) and think it is as good as all these very good DACs. When carefully matched for volume, none of my audiophile friends could tell them apart from each other reliably.