The problem with power supply decoupling through multiple lines is that unless you couple the grounds at your system, you are now injecting differential ground noise, which arguably is worse.
The concern with amplifiers is not average draw, but peak draw, which for an AB amplifier could easily be several times the fuse/breaker rating even though the average draw is far below the fuse rating. Over a 45 foot run, that could cause a large voltage drop at the top and bottom of the AC waveform when the amplifier capacitors are charging. For that reason, a 10awg run may not be sufficient (though the resistance may reduce EMI). I run a single 6awg, mini panel, outlets close by. That makes individual ground runs short between equipment, and a low resistance run back to the panel. I think it is a good compromise.
The concern with amplifiers is not average draw, but peak draw, which for an AB amplifier could easily be several times the fuse/breaker rating even though the average draw is far below the fuse rating. Over a 45 foot run, that could cause a large voltage drop at the top and bottom of the AC waveform when the amplifier capacitors are charging. For that reason, a 10awg run may not be sufficient (though the resistance may reduce EMI). I run a single 6awg, mini panel, outlets close by. That makes individual ground runs short between equipment, and a low resistance run back to the panel. I think it is a good compromise.