I've got a vox vr15, the amp is great, but the problem is, when i use the line out (or headphone out) into my laptop to record, i get loads of noise. The noise is like a middy crackling, but here's the weird thing, the crackling changes depending on what i do with my laptop, e.g. scrolling on a page produces a different noise, and unplugging the laptop charger changes the tone... odd. The vox has a value value pre amp, my solid state line 6 spider 2 15watt doesn't have this problem. What could be the problem?