Look at industrial surplus sites, medical equipment repair vendors, and online electronic component brokers.
A common failure where the auxiliary low voltages (+/- 7V) still work, but the main power rail for the subwoofer dies, resulting in no sound. hys3c210-cs power supply
In many cases, it is more efficient to replace the entire HYS3C210-CS module rather than attempting board-level repairs on individual capacitors or transistors. Look at industrial surplus sites, medical equipment repair