The TST2 is ok. Records from CD or radio are good. A cable replacement didn`t changed the result. Maybe that is just the normal behavior?! Noise on low frequencies are quite normal. Just love it and you are satisfied.
In reference to the topic are converting and recording different thinks (new tutorial?). However, your solution sounds like a stupid workaround for me. At least on Amiga you just choose frequency, stereo or mono and simple record that.