High noise when connecting guitar to jack

[amc252]

Hello everybody,

a friend lent me a Fender Strat and I tried to connect it to my laptop with the following setup:

HARDWARE
guitar jack > jack to minijack adapter > cable > USB soundcard microphone input

SOFTWARE
qjackctl + guitarix
system capture > guitarix head amp > guitarix head fx > system playback

I succeded in connecting everything and got the sound out of guitarix into the laptop output (headphones).
However, the base noise seems rather high as soon as I rise the pre-amp gain a bit and wondered what could be the cause and how could I troubleshoot the problem.

[autostatic]

Hello, is this base noise somewhere in the 50/60Hz range, so F#? And is there a difference when you're running on AC or batteries? Could be a grounding issue.

I succeded in connecting everything and got the sound out of guitarix into the laptop output (headphones).

Does the USB interface have a headphone output? If so, did you try that?

[haast]

In my experience the "tube profile" in the pre-amp section is noisy. When the "no tube" is selected noise is much less. Did you try that?

[amc252]

The laptop was on battery, so I ruled out a grounding problem, but changing the tube profile did the trick and the noise disappeared.
Thanks a lot for the tip!