Amp not switching off

[SharkGill]

To clarify I made the incorrect splices but realised before I hooked it all up so had to redo the wiring so no damage caused.

[HPsauce]

Dumb question time. Is there any way of inserting a manual switch into an appropriate circuit to turn the amp on and off definitively.
If so, the next step could be to have a relay to do it for you?

[SharkGill]

I was thinking of a switch mounted on the dash somewhere which I can manage but the whole floating ground and pop on power on/off is also bugging me as I don't have the know how to sort that yet.

[SharkGill]

The test is to connect a multimeter on ohms between the phono ground (outer shell) and the power ground. If you get zero / low resistance then the amp is not suitable. High resistance / open circuit is what you want. I don't know that any manufacturer actually includes floating / chassis ground in their specs though.

Another idea for just a sub is to use a speaker-level converter off the rear deck subs. The Bose amp will be responsible for the crossover then, which is not necessarily ideal, but a converter would likely side-step the floating phono problem.

is this the sort of converter you mean?

Screenshot 2026-06-04 170647.png

[Ronin]

Thats it.
You can see the caps, voltage dividing resistors and 2 small transformers (one channel each) that will step down the signal at a cost of signal degradation, loss of deep bass frequencies and other things dependant on how its designed internally.

It should also have a small flat head variable resitor that you can use to match the input voltage of the subwoofer/amp combo.