I was thinking about the vast number of beginners in countries where money for hobby activity is scarce, and knowledge of such things is, as well.

I'd guess that if one had a circuit, perhaps a PCB, that enters through the line inputs and puts the burden for interpretation on the software rather than on the user, it might be possible to work through such a set of problems.

We've seen the sorts of problems purported "students" have encountered using low-precison, low-bandwidth ADC systems. The sound hardware in most PC's is much better equipped, if not better suited for this purpose. The method I've suggested is simple enough to understand that most novices can process it mentally, once they've understood the consequences of AC-coupling. If the input circuitry is sufficiently solid, yet inexpensive, and the accompanying software is adequate to remove most of the "gotchas", it should, IMHO, be achievable. Given the difficulties are not totally insurmountable, software should be able to smooth out the wrinkles considerably.

There are, of course, design issues to be hurdled and software to be crafted. However, it's a PC and not a small MCU, that does the work. The human interface could easily be handled in one of M$'s "Visual" products, which would also make the display management pretty reasonable.

I haven't yet put any thought into the problem, but it does seem reasonable to me, at least for now.

RE