Ground Busses

Patrick posted some interesting facts about ground buss
connections, which I have extracted from another thread
and pasted here, because I think the subject is im****tant
enough to warrant  its own thread.

He wrote:

> The 0V rail of the preamp should be a short buss wire about 100mm long
> with ends connected to the RCA plug 0V bodies at inputs and outputs.
> ALL parts with OV connections should be made to this buss,
> and the CHASSIS or CASE connected via a 5 watt 27 ohm R, and the case
> taken to the  green/yellow wire to the wall socket so the case can't
> become live to mains or the B+. There should be NO direct connection of 
> the OV buss to the case.
-- 


I ask:

In other words the mains supply case should be bonded to the case,
and the 0V (signal grounds) taken to the ground point via a 27 Ohm
5W resistor?

Why is this?

My experience with ground buss amps is limited. I have never been
able to make them quiet enough. I found that the exact position in
which a wire was placed on the buss was critical, and that a difference
was audible.It may be there is something lacking in my implementation
of the buss.

I prefer to use a star ground, as follows.  Earth (ground) connection
from the supply - the only green yellow wire in the amplifier is taken
straight to the chassis bonding screw.  The input and output RCA
signal connectors I used are the isolated type (Neutrik NF2D)

http://www.neutrik.com/uk/en/audio/210_3470585/NF2D-B-0_detail.aspx

I run a separate wire (black) from each of the RCA input and output
ground tags to the star ground. Signal wires on the input side have
their ****elds connected at the RCA socket end only.

On the psu, I run separate grounds (heavier wire) from each cap
separately to the star. They are not linked.  The only exception to
this is the 1st (reservoir) electrolytic , which is connected directly
to the neg terminal of the FW bridge, and then to the star.

This is a topology I have seen used on amps that perform well,
and has been taught to me as a good solution.
It seems to work. My 50W power amp has only 80µV
of noise (-108dB) and no audible hum even with the ear
against the speaker (Tannoy Gold 15 inch)

Regards to all
Iain