I just completed building my BIII and have an interesting problem. One input on the 4-channel S/PDIF input module works fine, no drops, sounds good. The other 3 inputs (including one connected to a TOSLINK module) do not stay locked. When connected to these inputs, the lock LED blinks sporatically and the audio output sputters. I'm using a Squeezebox as the test input source.

Here is my configuration:

BIII with 4-channel S/PDIF input module
One TOSLINK module connected to S/PDIF input 4
Legatto I/V Stage
Placid HD PS, Vout=5.22v, total current=500ma, shunt current=50ma (measured warm)
Placid HD BiPolar PS, Vout=+/-14.8v, total current=255ma each, shunt current=50ma each (measured warm)
SW1: all switches in the off position
SW2: all switches in the off position except SW2:8 which is in the on position

I tried adjusting the DPLL bandwidth but it made no difference.

I suspect I have a problem with the wiring from the input connectors (and TOSLINK module) to the 4-channel S/PDIF input module. Does that sound likely? Maybe the wiring on the one working input just happens by chance to be ok? I'm using standard Neutrik RCA connectors. I know they are not ideal but figured it was probably ok after reading one of Brian's posts that said most commercial offerings use standard RCA connectors. Connections to the board are loosely twisted 26 gauge solid silver/teflon wire. The wires are about 3" long. What is the right/best way to wire up the inputs? Is a wiring change likely to solve my problem?

Leon, good idea, thanks. I swapped the wiring at the S/PDIF at the 4-channel S/PDIF board connector. The symptom followed the wiring/RCA jack. (The good RCA jack connected to another S/PDIF position works fine.) Interestingly, the TOSLINK, which was not changed other than the wires were moved a bit, is now locked on.

It seems the wiring to the jacks is sensitive. What is the best practice to wire up the jacks? Maybe I just need to reroute things? Is it best to use shielded cables? If so, what type?