Listening to CDs only via the coaxial audio output - that's not how I use the Sony BDP-S1700. I have connected the Sony BDP-S1700 to the TV using an HDMI cable and that's how I watch movies from video DVDs and blu-ray discs and from external USB discs.

But to answer your question, I have used the Sony BDP-S1700 as a standalone - without a connection to the TV or any other device. At the back of the Sony BDP-S1700 I plugged an RCA connector into the coaxial digital out output. The cable with this cinch plug is a cinch-to-3.5mm converter, so that I could connect a speaker with a 3.5mm connection cable to the other end of this cable. Then I inserted an audio CD (with *.cda files) into the front of the Sony BDP-S1700 and pressed "Play" on the remote control of the Sony BDP-S1700. What could you hear from the speaker ? Nothing !

Then I tried the following: I used the Sony BDP-S1700 again as a standalone device and this time I also plugged a cinch plug into the coaxial digital out output on the back of the Sony BDP-S1700. But this cable was a normal cinch-to-cinch cable. I plugged the other cinch plug at the other end of this cable into the audio input of a digital-to-analogue audio converter. And I connected the speaker with the 3.5mm cable to the audio output of the digital-to-analogue audio converter. I then inserted another audio CD (with *.cda files) into the front of the Sony BDP-S1700 and pressed "Play" on the remote control of the Sony BDP-S1700. What could you hear from the speaker ? Everything ! But the volume cannot be adjusted with the remote control of the Sony BDP-S1700. The volume can only be adjusted if the loudspeaker itself has a volume control wheel or slider.

In other words: you can only play CDs via the coaxial audio output of the Sony BDP-S1700 without switching on the TV.

With the TV, however, it is more convenient because then you have a graphical interface and so it is easier to navigate to different directories on the audio CD and listen to specific audio files within these directories.

Good question! Unfortunately, I never tried it. Maybe somebody else did it. If so, please give us a hint!

I don't think so, at least I've never tried it. Because I don't have any music CDs.