The RMX normally sits in the master output line between mixer and speakers or mixer. I don’t really see the value add of an RMX with a controller and Serato. Serato is packed to the rim with FX and they are generally high quality. So you would use them only for the mic channels.
On a bigger mixer you would use an aux channel for that. You could then send a signal from any given channel to the aux bus with the RMX and it would come back. You would then mix the aux return with the original signal to get the desired effect.
The MG06X has no aux though. Lucky for you, you bought the X version which has FX that can be switched on or off on the mic channels.
So, unless you want something outlandish on your mic channels, I’d say retire the RMX, use the Serato FX for everything controller related and use the MG06X FX for your vocal mics. While not much by way of setting (pretty much factory default), I know the Yamaha FX to be pretty much spot on for best practice.
Hope that helps some.
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