Originally Posted by: metalfaithfull ... exept a low volume hum that iv never had before.

I've had this exact experience with bad cables , and it disapears when you plug into good or new ones.

I haven't thoroughly inspected that (I just throw the cables and get new ones instead) , but I believe it should have something to do with very slightly touching of the two wires of the cable at some point of its length , so then lowering the resistance between the two wires from a practical infinity compared to short circuit at full volume , to a finite value compared with the corresponding value of the higher resistance you put in when you lower the volume.

Anyway , if you have a multimeter that can measure resistors up to hundreds Mega Ohms , check out the resistance between the two conductors of the stuff you made , and compare them to a good working cable (if it's a very good cable , you may not be able to measure it's resistance , due to it's very high value).
If you found less resistance , buy new jacks and stuff , and redo your job more accurately next time.... And I hold copyrights for this theory . :p