Turntables are grounded to the mixer. Pre and power amp and powered sub I have no idea about (no grounding cables). I did wonder about grounding the 2x4 chassis?
The crossover chassis will be grounded to the same point as all the other analogue signals via the phono plugs. If the PSU is grounding it to a separate point, that will create your ground loop.
Turntables are grounded to the mixer. Pre and power amp and powered sub I have no idea about (no grounding cables). I did wonder about grounding the 2x4 chassis?