I recently upgraded TH2 Producer to the full version and playing my guitar the Hum was really bothering me, so I started to investigate (not know anything really)
I have an Epiphone 335, so humbuckers, and use this cable from Thomann
http://www.thomann.de/gb/cordial_cci_3_pr.htmplugged direct into my Roland Quad capture, into my new laptop.
I noticed that if I touch the metal part of the jack casing, the hum dropped. I tried the ground lift switch on the Quad Capture and nothing. I feared electrical issues with the Guitar (the selector knob for the pick ups has failed, so I just have a choice of either, but not both). Then realised to rule out the guitar, I just unplug it, but leave the cable in. It's not the guitar, seemed the cable, so investigated the soldering, but it's fine.
Then it dawned on me, the laptop is new. I pulled the power cable out of the laptop, and bingo the noise llevel dropped massively. not completely, but nearly all of it. So that's a workaround.
Now on some noise still remains, but I am wondering if I can get it cleaner.
Will a cable make a difference?
Should the ground lift of made a difference on the quad capture?
When I hold my fingers against the strings there is small improvement, does this indicate and guitar issue?
Should I just put up with it?