VU meter grounding

I'm building a seperate VU meter unit with salvaged parts based on an opamp buffer.
My aim is to build fig 4 of this page :

Driving VU and other AC Meters - Simple High Performance Circuits

The article states that : " in both circuits it is important to note that the rectifier is connected to a separate ground from the rest of the circuit. This is because the non-linear rectifier will cause the ground current to be a distorted version of the audio signal at the input."

How do I create seperate grounds ?

Would it be ok to send the rectifier gnd to the 0V of the split power supply I have built to power the unit. I.E. the centre tap of the transformer ?

The ground just has to be on a separate wire from the star-grounding point so its current doesn't flow in any other circuit. That could lead to distortion product bleeding into other paths the signal takes.

A return current from a linear version of the signal can only cause very slight level change in the main signal via IR drops in the wiring, as its exactly the same signal, so you don't have to be so scrupulous about grounds there.

Where separate signals are involved star-grounding is needed to avoid cross-talk. Just treat any rectified or distorted current as if it were an interfering signal.
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