I'll open by saying assume I'm an idiot 
I have much interest but no experience with Theremins, and I was just gifted an Open Theremin v4. I'm having a lot of fun playing around with it, but there are some problems I haven't solved yet. For the moment, I am trying to come up with an inexpensive and casual portable setup.
I haven't managed to figure out grounding, yet. I'm looking at an inexpensive thing on Amazon that has a grounding plug for your socket and a little wire I could clip to the OT, but I'm very open to suggestions here.
I have a little cell phone battery bank that's working well, but the only thing I have as far as speakers go is a set of headphones. Would mono headphones be better? Would a Bluetooth speaker with an aux cable work, or a mini-amp? Any recommendations are welcome.
Thank you 