Anyone can help with a question in use of Boulder 866....

If you visit the Boulder website they should have the driver you need for the PC to recognize the Boulder DAC.   

Once you load the driver on the PC it should recognize the Boulder USB DAC when plugged in. 

USB isn't always plug n play, sometimes it's plug n pray.   

It may only play USB sticks or drives.   Test with one and see if you can play files.  

Thank you so much for your response, very helpful and valuable.

I will go to Boulder's website to see and do..

Thank you again!

Good luck.  If they don't have a driver then it is most likely for playing USB drives which it should recognize 

@audiowin55 this is a question that can be answered by either the owners of the Boulder 866 or the 866 manual. 
There are two versions of the 866 - Analog and Digital. Both feature USB input. The Digital version includes the built in DAC that can be fed thru AES or Toslink. The USB input is for a memory stick or a USB remote. It will not work with streamers or computers. 
The Analog version USB input is used for the USB remote. 
 

So..,if you have a Digital version of the 866, the way to get sound from YouTube is to AirPlay to the 866 that’s connected to your network via Ethernet cable.

Which version of the 866 is it?
 

Digital version.

So great information too from audphile1, thank you so much.

To go through Airplay to have YouTube get on is an especially great clue. Thank you for reminding me of this!

👍

You should get aserver ar some point a pc is not a high quality device for music output

Let me guess... an EVO 432 ?   

We don’t have to worry about pc as a source with the 866 as it’s impossible to connect with USB. But the digital version of the 866 is a Roon end point so using it that way makes sense. 

Thank you everyone. Now I have my question completely answered and the problem solved.

I want to use 866 for Tidal. Can it directly do streaming from Tidal.

Going through some steps in it, I went to " Tidal not logged in".

What to do to stream down those tracks in Tidal to the 866?

( I have Tidal account).

Thank you so much again!

I have always plugged my desktop sound card into a receiver, and it works great!  You are trying to use an amplifier that has no preamp. Try plugging your PC into your preamp or something that has a preamp in it.  Oh and be sure to not use any Phono inputs.

All the best.