You need to isolate the speaker(s) and control their connection to the amp.
Parts:
12VAC transformer, 24W or a 12VDC 2A wall adapter.
AliExpress 30A speaker protector circuit AIYMA 900W. I used their 30A mono device. $7.60
Install a toggle switch OR smart device Alexa or Kasa (By TP-Link) smart WI-FI plug HS103.
Connect between amp and speakers. Mount with hot glue gun.
Now control amp with Kasa app on phone or use toggle switch or use Alexa to power on or off speaker.
Parts:
12VAC transformer, 24W or a 12VDC 2A wall adapter.
AliExpress 30A speaker protector circuit AIYMA 900W. I used their 30A mono device. $7.60
Install a toggle switch OR smart device Alexa or Kasa (By TP-Link) smart WI-FI plug HS103.
Connect between amp and speakers. Mount with hot glue gun.
Now control amp with Kasa app on phone or use toggle switch or use Alexa to power on or off speaker.