Puritan PSM 156 connecting Puritan Grounding Products?

Why not use the ground master city.  It just plugs into your outlet and connects to the PMS 156.  It was intended to be used without an outside grounding rod.

“My initial thoughts are the GroundMaster, coupled with the GoundMaster City (no inclination to attempt driving an 8ft copper rod through my garden soil).”

OP, do you mean the RouteMaster coupled with the GroundMaster City? I have that combo, but not the PSM156. I believe that you can connect the PSM156 to the RouteMaster, along with your other components. From what I understand, however, there may be some benefits to running a separate GroundMaster City just for the PSM156. Best to check with your dealer, or PAL directly.

Conduct the chase with a professional.  I made the complete run with someone smarter than me, Tom at Big Ear Stereo in Tempe.  He gave great insight into all of the Puritan products and the why and how of each one.  I even grounded all of my components to include my ATC towers (active).

Yeah, it's a rabbit hole, but there is a very nice bright carrot at the end.  Each piece added, or in this case subtracted, for improvement of the system.

He even screamed at me, correctly so, about my Netgear meta data transfer. Anything to clear frequency nasties from the chain.  I got rid of it.

@jea48 during your reading you've missed some critical points.
The Puritan GroundMaster is not directly connected to the safety earth and has no bearing on that.
Also, it deliberately provides isolation against low (power) frequencies as a safety measure.

What it does do is by virtue of its, "12 Individual Alternately Tuned Frequency Guides" provide a low impedance independent path to ground (via copper wire ;) for electrical noise.

It is very effective.

I have the ground master and the pms-156. I want to ground only 2 units. Must I buy the route master or can I get away with running the two through the ground master?