Ultimate circuit probe

[egasimus]

Hey there. I've been wanting to build myself a standalone audio probe for a while - which is a simple enough build that I'd like to add some extra stuff to it, most importantly a LED that reacts to DC and subsonic frequencies. This'd be really neat to have - it'd let you easily scope basic LFO and envelope signals.

However, circuit design is as big a mystery to me as ever, so I need to ask you guys for some pointers. Could I do this with a 386 chip so it can easily drive speakers?