Thank you for your post and welcome to the Bose Community.
Could you please explain your question a little bit more, please? Where are you seeing the "2.0"?
I look forward to your response.
Charlotte G - Community Support
Thanks for posting and updating us on this.
2.0 PCM means that the system is sending a 2 channel signal. You can find the 321 Owners manual and all other information here.
Apr 12, 2020
PCM is Pulse-Code Modulation. It's one of the ways the computers like the ones that drive the 321 and cable/satellite boxes 'think' about audio information. The 'PCM: 2.0' display means that your 321 is receiving a digital stereo input connection.
You can change it by changing the input signal. For example, let's say your AppleTV goes to your TV through an HDMI, and your TV goes to your 321 through an optical cable. If you play a movie with sound formatted in Dolby Digital 5.1 (five speakers and a sub-woofer), the 321 will show 'DOLBY DIGITAL: 5.1' The 321 is converting the 5.1 signal to its 2.1 system (two speakers and the subwoofer) like it was designed to.
The 321 receives digital audio through either the Digital COAX Audio or Optical connections.
On the other hand, if you flip the 321 to its FM tuner and get a strong signal, the 321 will show STEREO, because the 321 systems mostly pre-date digital radio.