Depending on the kind of music you want to play on the theremin, you MAY need more than just a pair of headphones if you want to play without disturbing anyone. If, for example, you wanted to practice by playing along with your favorite music, or a pre-recorded accompaniment of some kind, you would need a small mixer that could accept and mix more than one device. Also, if you want to experiment with FX (reverb etc.) of any kind, a stereo mixer is essential.
If your goal is to play precision theremin (as opposed to SciFi FX & fright stuff) then, unless you have perfect pitch, you will need a reference tone so you know what note you're playing.
MACKIE makes some excellent products for this kind of thing that you could pick up on ebay.
Good luck with your new adventure!
By the way, the most common mistake that theremin newbies make is to believe that they don't need to choose and learn a specific method for the instrument, and that they can just figure it out for themselves as they go along. Nobody would do that with the violin or the cello, but they do it with the theremin all the time.
If your goal is to play precision theremin (as opposed to SciFi FX & fright stuff) then, unless you have perfect pitch, you will need a reference tone so you know what note you're playing.
MACKIE makes some excellent products for this kind of thing that you could pick up on ebay.
Good luck with your new adventure!
By the way, the most common mistake that theremin newbies make is to believe that they don't need to choose and learn a specific method for the instrument, and that they can just figure it out for themselves as they go along. Nobody would do that with the violin or the cello, but they do it with the theremin all the time.