BlueSound Node 2 - connect to pre-amp direct or to Oppo UDP-205 and then to pre-amp

Though the integrated DAC in the Node is good for the price, I would output to a better DAC, if possible.
So, yes, use the Oppo.
B

In theory the OPPO DAC should sound better but I would just try both options.
You never know and only your own ears can decide.
Good luck

Try both, but you may decide there's not a lot of difference. I tried my node 2 through my OPPO 105D and it does sound a little better, but not much and I like not having to turn on the OPPO and the TV to listen. 

I bought the Node2 a few months ago to better the sound over the Sonos, which it did. at the time I was using a Rega DAC. However I did for about a week run Node2 directly to PreAmp and it was much better than the Sonos. And thru the Rega DAC it followed suit. I recently traded the Rega in for a Chord Cutest.
Sorry I took the long way around your question, so yes the Oppo should sound better, I also have the Oppo Bd105 but have chosen a separate stand alone DAC.

theo,
A bit off topic, but was wondering how the Chord Qutest would compare against the Ayre CODEX. Both are similar in price. I too, stream with the Node2.

mr_m, I never got to try the Codex , although I was attracted to it, just never pursued it. I would love to try the newer Ayre DACs, but budget didn’t have it at the time I bought the Cutest. As mentioned it provided the sound I wanted and was much more pleasing than my previous DAC. Sorry I couldn’t give you a better answer. But should you get a chance to make the comparison, I would like hear your findings.

use Mac Mini as media player and connect it usb with oppo 205, set Tidal MQA playback direct through and let Oppp EES 9038 chip to decode whatever files format . if you use window's system, Use Foobar2000 to play back DSD files and PCM files.

You should connect it both ways to play MQA tracks through the Node.  A MQA track sent from the Node will output at 24/96 to your DAC so either way it sounds great.  The Node's DAC is pretty good, I should say it's analog outs sound good.  I think DACs have matured such that it's really the implementation and quality of the analog stage that defines the sound.  So try both and see...