Hopeless Theremin Recipient Needs an Amplifier/Speaker to Get Started

My partner bought me a moog etherwave plus for christmas and I have no idea what quality amplifier to get. I've tried to do a little research, but I'm not quite getting a good idea of what exactly I need, or if I even need a particular type of amplifier at all. Any advice is appreciated, I don't want to spend more than ~$200. 
Thank you!

Really any amplifier will work. If you have a stereo with a quarter-inch input (or you have a quarter-inch cable that goes to whatever input your stereo takes) you can just hook it up to your stereo. If you have a guitar amp around that will also work fine.

If you don't want to use your stereo and would like to buy an amp to use with the Etherwave Plus any of these Monoprice units would be suitable:

Cheap Option: https://www.monoprice.com/product?p_id=611710 (10W, good for small-medium performance spaces)

Midrange Option: https://www.monoprice.com/product?p_id=611720 (20W, probably fine for medium-large performance spaces)

Expensive Option: https://www.monoprice.com/product?p_id=611705 (5W, good for practice or small performance spaces. This one is a tube amp & reasonably "hackable" if you're electronically inclined, but that sort of tone coloring isn't really required with a Theremin so unless you intend to use it for guitar as well I would go with one of the cheaper units.)