Ground reference for DC fan supply?

[TOA Bassman]

I'm about to add a cooling fan to my TOA HA-356/Bassman project, mainly just because I can...

I scrounged a 75mm 12V 300ma DC fan from an old pc and jury rigged it with a regulated 12V 1.2A wall wart - it's quiet mechanically and electrically and keeps the thing very cool so I'm going to install the guts of the wall wart into the chassis, taking power from the mains switch.

Should I ground the DC output -ve side? Any ripple which is present is undetectable to my ears anyway, so are there any advantages or disadvantages to leaving it floating?

[eschertron]

As long as the secondary of the 12v supply is isolated from the mains side, I don't see why you couldn't reference it to DC ground.
OTOH, since the 12v is not near the signal path, does it matter? Hopefully, more experienced opinions will weigh in.

[J M Fahey]

Agree.
You donīt NEED to ground the fan supply, which will be just as happy floating, but if you wish, it should add no problem.

The possible source of interference (it drives you nuts if, say, the reverb tank is close by) is the magnetic fan motor generated switching hash, so keep fan itself away from sensible points.

[Enzo]

It works fine now, un-grounded. So stop fixing it. Why bother to ground it? All I see is the potential to couple fan motor noise into the audio circuits.