It's always interesting in audio (or lab/automation) how you want to filter out noise (isolated ground, etc.), but naive ways of doing that can cause serious problems.
Yes, naive ways cause big problems. While I've seen people do many ill-advised things in home and studio audio, professional concert audio is decidedly more buttoned down:
Grounding is not isolated, but NEC-compliant star grounded (See NEC 400.8, 520, 525, 530 (movies), and 640 (carnivals) )
Loop area is actively minimized
Signal transmission is via instrumentation amplifier topology (i.e. differential)
Shielding is designed to minimize shield current induced noise (SCIN)
