Hope you dont mind, lets do some other test.
A. With the RPi3B still connected to the TCL TV (either by long or short HDMI cables), and both connected to UPS, RPi3B connected via LAN cable
1. set the audio to output from the TRRS jack.
2. plug a headphone to the TRRS jack
3. play an audio /video file (a file that played properly on the RPi2B)
4. check for choppiness in audio from the headphone
B. Same setup as A, but remove connection to TCL TV, access the RPI3B via VNC from another pc (or from RPI2B). This we try to eliminate the TV as the source of "choppiness"
C. Same as A, but power source not from UPS but from another outlet. This we try to eliminate the power source interference
D. Same as B, but power source not from UPS but from another outlet. This we try to eliminate both the TV and the power source interference.
"Don't come to me with 'issues' for I don't know how to deal with those
Come to me with 'problems' and I'll help you find solutions"
Some people be like:
"Help me! Am drowning! But dont you dare touch me nor come near me!"