Zombie thread alert!
So a year later, having not used my Archon nearly as much as I would like, and also not using the effects loop at all, I start mucking about again and notice the loop noise issue (again), which I never got fixed.
I was reading yesterday that amps with effects loops are somewhat expecting to have rack-mount effects put into that loop, not necessarily pedals. So last night I experimented with a rack-mount delay I have, and the noise levels dropped considerably. This is possibly attributable to the impedance matching better just as much as any other factor. I would be curious to know if the changes/fixes to the Archon effects loop made using the different resistor are impacting gain and impedance, or just one or the other...
So, I just found info on the impedance of my rack-mount delay - it is 10kOhm on input, 1 kOhm on output (and the unit expects levels at -10dB, does not say if dBv or dBu). But I lack info on the send and receive impedance of the Archon. I'm hoping I might gain some knowledge from the group as to what might be typical of a PRS amp, if nothing specific about the Archon is known.
(The very simplified Archon owners manual from the PRS website lacks much specific data...)
EDIT: one more thing:
Typical Boss pedals have input impedance of 1 MOhm (I MegaOhm), with output impedance recommended to be 10kOhm or greater. Thus, the rack mount is much lower impedance than a typical Boss pedal.