The purpose of R0 in Aleph 30 circuit

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I have a question with regards to the actual purpose of R0 in Aleph 30 circuit. It's been said that this resistor breaks ground loops, but I can't quite figure out how it does that. I mean, would it make any difference if R4/R5 were connected directly to signal ground, as it seems like signal ground connects to those resistors through R0?
http://www.passlabs.com/downloads/old product/a30manr0.pdf
 
I thought initially that this is a resistor separating signal ground from output ground, but it does not seem to be a case (you can notice such resistor on National's LM4780 evaluation board). So in most cases it's probably not needed anyway ( as I'm also not using the input diodes).

I'm still considering improving the ground scheme on the A30 board. I recall Zigybait commenting that running separate ground paths from current source circuit and the signal ground to main star ground point improved performance.
 
The one and only
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As I recall, R0 simply helped to break the RCA connection
loop going back to the source equipment. There was a
little less noise this way, and both the input and feedback
referenced to it, so it didn't compromise performance. If you
don't need it, there's no requirement to use it.

:cool:
 
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