Why didnt u buy an Audio interface instead of investing in an expensive sound card?
These are some quick things that u can try:-
1) Use ur friends external Sound card on ur computer and test it if the problem is ur sound card or ur pc
.Similarly test ur sound card on ur friends PC
2) Try using a different software for recording just for testing purpose. There are lots which can be used such as Audacity. Its freely available for download.
3) Try changing the connector
4) Try with ur friends guitar.
This same humming noise use to come when i tried using Amplitube. I didnt use that software after that. And also there was some problem with the Mic that i was using....
Guitars : USA Fender Stratocaster 1981 Collectors Series, Ibanez RG420eg, Cort X6vpr Snake skin, Custom Tele Style Guitar
Processor : Boss ME 70
Amps: Laney Cub10(4 Sale), Roland Microcube
Recording : Focusrite Scarlett 2i2, Shure SM57
For Sale: Sansamp Tri-AC