Electronic kits can be worthwhile for us as field recording geeks. This time I bought the Kemo kit for a Listening Stethoscope since I was interested in amplifying the softest of sounds, such as wind blowing through the trees. For the price of 11.80 €, I was skeptical at first but with a little soldering the board works just fine. The official product description is quite shady when they say that their device enables you to listen through walls, etc. Apparently somebody lacked the fantasy of doing something legal with the stethoscope.
However, if you look for a quick and dirty recording of soft sounds, the Kemo Listening Stethoscope is a good choice, since the IC’s triple op amp enhances ordinary sounds very well. But still, don’t expect crystal clear one-to-one realistic recordings, you need to be able to either filter out or ignore the high frequency noise. Another challenge is to keep the right distance between mic and headphones because the device is so sensitive that it is prone to feedback. Needless to say, you’ll only get a mono recording.
For you to get an impression, I made a very dirty recording out of the window with somebody practicing the violin next door. I connected the headphone output with a male mini jack that went into the line in of my old Tascam DR-07.