Output jacks and NFB

[studiodunn]

So I'm about done wiring things up and started thinking about the Output jack(s)

The original Bassman100 had only a 4 ohm tap and a non-isolated jacks.
The new OT has 4/8/16 with the NFB running to the 8ohm.
Should these output jacks be isolated to eliminate the chassis ground for the OT?
I'm trying to wrap my head around Mr Aiken's explanation, but I'm not seeing it in my head.

[frankdrebin]

You need the ground reference for nfb to happen, if you use isolated jacks run a wire to the pi ground point.
Whatever ohm output you choose it's just a matter of selecting the appropriate resistor value.

[Roe]

Ground the output jacks together with the phase inverter if you use the standard long tail circuit with NFB