isolated or non-isolated psu for UcD in a car?

[zilog]

I am playing with building an SMPS to power a couple of UcD amplifiers in my car. The input stage of the amplifiers is depicted here: frontend.

I would like to have the SMPS non-isolated with the car earth connected to the output center-tapped ground. The reason for this si that I want to play with adaptive control loop design as opposed to the fixed nature of the loop you get with opto couplers. This will of course feed lots of common mode-noise and harmonics into the frontend of the amplifiers. My question is if this will make any noticeable difference on the sound.

The frontend is fully differential, so I can wire the car stereo so it doesn't feed any current into the coaxial low-level cable shielding, my main concern is with the cmrr capability versus the nature of the common mode-noise I can expect due to this arrangement.

[Eva]

Considering that the typical PSRR of UcD is 65dB, forget even about regulation. It's all a big waste of time.

Powering CPUs (or just charging batteries) would be a different story.