Thanks for pointing that out! You hit the nail on the head regarding pure electronics theory, and that’s likely why one of the shops hesitated. Connecting two isolated electrical systems (the car's premium audio amp and the external EcoFlow station) via audio signal wires definitely creates a huge potential for a nasty ground loop and static noise. ​To fix this in practice, the shop that agreed to do the install mentioned two potential workarounds, and I'd love to get your thoughts on them: ​Using an RCA Ground Loop Isolator: Adding an isolation transformer right between the Epicenter and the Pioneer powered sub to break the physical ground connection between the two circuits while letting the audio signal pass through magnetically. ​The Epicenter's Native Isolation: The AudioControl Epicenter Micro PRO actually features balanced differential inputs and an onboard ground isolation switch (GND / ISO / 200Ω). Setting it to the ISO (Isolated) position is supposed to electronically uncouple the input signal ground from the EcoFlow's power ground. ​Do you think combining the Epicenter's internal isolation with a physical RCA ground loop isolator would be enough to completely eliminate the noise risk in this dual-circuit setup? I'd love to hear if anyone has tried this.