OK, I'll deal with the grounding later, will need to digest the Davenport grounding article - not so simple for me. 
Another question: I will be connecting a twisted pair from each jumper to a pair of pins on the switch. There are six jumpers and six pairs of pins on the switch. Therefore, I will need six pairs of wire, each pair individually shielded and having a drain wire. Is there are any issue to the wires being twisted - should I untwist them - or is it in fact better for them to be twisted? Note that it is just one and the same signal flowing from a jumper's pin to the switch then back to the other pin of the jumper to make the signal connection. I'm not sure whether a twisted pair is beneficial or detrimental in this scenario. Any thoughts?
Another question: I will be connecting a twisted pair from each jumper to a pair of pins on the switch. There are six jumpers and six pairs of pins on the switch. Therefore, I will need six pairs of wire, each pair individually shielded and having a drain wire. Is there are any issue to the wires being twisted - should I untwist them - or is it in fact better for them to be twisted? Note that it is just one and the same signal flowing from a jumper's pin to the switch then back to the other pin of the jumper to make the signal connection. I'm not sure whether a twisted pair is beneficial or detrimental in this scenario. Any thoughts?
Would the picture below help? The jumpers and possible grounding screws are encircled in red. There are three possible grounding screws now. Two are on the board and one is on the chassis.
I don't know what to test for or how. If none of the screws is causing a ground loop or hum, I still wouldn't know which one of them is best.
Does it mean that if none of the screws is causing a ground loop or hum, I can practically choose any of them? That the difference between the best and second best grounding point is negligible? Or do I have to find out whether the board uses star grounding and if so, locate the star ground point and ground to that?
Thanks!
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I think we are losing sight of the objective. Nothing needs to be grounded except possible shields of cables. These would only be grounded at one end so signal not passing through.
Back to the beginning:
You want to extend the jumpers to the connector block circled (oblonged!) in your photo.
The simplest way to do that would be a short length of IDC ribbon cable. Cut a rectangular slot in the box lid and fit a male IDC pin header pass-through. Make up a short (3"?) 12 way ribbon cable (easily done by squeezing the connectors in a vice - lots of websites explain how).
Cable connects between PCB headers (with jumpers removed) and underside of pass-through header. Now move the jumpers to equivalent positions on top of the box.
The beauty of this is that you can test it before you cut the metal or solder anything.
Just attach the ribbon cable without the lid and try it.
Try and resist being to anal about whether it is perfect or not: If it sounds good without extra noise or hum, it works.
My bet would be that the impedances are pretty low and it will work well. A schematic would really help here.
Back to the beginning:
You want to extend the jumpers to the connector block circled (oblonged!) in your photo.
The simplest way to do that would be a short length of IDC ribbon cable. Cut a rectangular slot in the box lid and fit a male IDC pin header pass-through. Make up a short (3"?) 12 way ribbon cable (easily done by squeezing the connectors in a vice - lots of websites explain how).
Cable connects between PCB headers (with jumpers removed) and underside of pass-through header. Now move the jumpers to equivalent positions on top of the box.
The beauty of this is that you can test it before you cut the metal or solder anything.
Just attach the ribbon cable without the lid and try it.
Try and resist being to anal about whether it is perfect or not: If it sounds good without extra noise or hum, it works.
My bet would be that the impedances are pretty low and it will work well. A schematic would really help here.
I have already bought the materials - Belden 8773 cable, DIP switch and all - so it's kinda late to change plans. I'm so eager to start working on this now. You know how it feels... Gotta bring out the soldering iron. Oh, this is getting addictive!
Anyway, I think I'm just going to ground the wires to the chassis of the input pot. Whatever ground the input pot is connected to (analog ground?), I'm sure it's the right ground for the wires because the wires are passing analog signal, too.
Thanks, Cliff, and everyone for your help! On my next project I'll remember your advice to not be so anal... if I can help it.
I really got to teach myself that there is a point of diminishing returns...- Status
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