Setup for EV plus — amps

Hi there,
I’m new for theremin and currently building my setup. I’m professional musician and completely clueless when it comes to STEM… be patient please 😅 I’m doing my best!
I got Etherwave Plus (serial number 9000) and mic stand. I’ve just ordered also ESPE01 mod which friend of mine will install for me (engineer). 
The instrument needs calibration which I’m going to do but currently I’m struggling with amplification. I think I’ll go for monitor but not sure which one, and should I get one or a pair? I have opportunity to buy pair of Yamaha hs5 monitors in very good condition and price. Do you think they are suitable? I’m afraid they’ll be too loud for small venue (I’ll be practicing at home which is really tiny)…
I feel so lost in all this technic stuff around theremin, really hope you’ll help me!