thinking about buying one. A few questions

Hmm, I currently don't have a microphone stand, nor an amplifier. Is there any sound coming out of it without it? Because I also cannot imagine my neighbours would enjoy the sounds much. I will probably plug a headphone in it if it doesn't have any sound coming out of it

You could put it on some kind of (wood/plastic, preferably not metal) table or (bar)stool as long as the volume loop stick out at the side and has nothing directly under it, although a microphone stand would be best. You could play it listening though headphones, but the sound through the headphones output is not very nice. I jumpered it for pitch preview which can be useful in some live / jamsession situations to come in on the right pitch, or a tuner can be hooked up to it for that purpose. So something that acts as a (headphones) amplifier an also has some tone dials, and is plugged into a safety ground mains socket is to be preferred. When you would listen to the theremin with headphones plugged into the theremin's headphones output, you would still need some way to provide grounding, which just like old AM radios a theremin does need and the European power supply does not provide, so that is expected to come from the amplifier it is plugged in. This also could be something like a HiFi, and a cable that puts the (mono) audio signal on both left channels. Sometimes just using a long cable on the floor going to the amplifier provides enough (capacitative coupling to) earthing to make the theremin playable.

By now I have it. I got it working and all and I can even play some really simple tunes, even if it is slow and a lot of false notes. But something I've noticed is that the sound coming out of it isn't really pleasant to the ears. When I see the videos of theremins, it shows the difficulty, but the sound itself seems warm and clear. Is there something I am doing wrong? Because I don't think that the moog etherwave plus really can sound better as it right now.

When I watch introductionary videos, pretty much the first thing I'm told is to install modules, which, from what I understand, requires me to open it up and solder and such... something I don't see myself doing. Do you guys have any tips for a beginner? Mind you, I am not handy nor have knowledge on electrical stuff. Most of what DreadVox wrote isn't something I understand.

What are you listening through would be my first question? Home Hifi amplifier, combo amp or only headphones connected to the theremin's headphoes jack? Is it connected to safety ground (Dutch: is de theremin verbonden met een versterker die verbonden is met randaarde)?

I currently have it plugged into my speaker set that I also use for my pc. It has this... box with settings and such. I guess it's an amplifier. It had an aux input at the back and after getting a mini-jack to mini-jack cable + a part that turns mini-jack into maxijack, I could use that to get sound of it.

Now about your questions: The moog etherwave plus doesn't appear to have a headphone jack. All it seems to have is either these ports with pins it it that I guess is used for power supply, and one maxijack one. About the things you said, hifi amplifier, combo amp, these two I have no idea what they are.

About the safety ground thing: In the manual of a regular moog etherwave it is mentioned that you should connect the socket to one that is grounded, so with that metal pin. But the moog etherwave plus doesn't seem to have that. The power plug isn't one with a metal thing, the type of thing that requires grounding (from what I understand). It is just a regular, modern power plug so I figured this one doesn't need it.

Hm, if your theremin doesn't have a headhones out next to the audio out and no dial marked 'PHONES VOL', it is not an Etherwave Plus, but an EW standard... A pc speaker set does include an amplifier, so that is at least something, but these usually also plug into a mains socket without connecting to the metal thing on the side. A Hifi amplifier is what you might have for things like CD player, record player etc, may or may not include radio, nowadays is often called 'receiver'. A 'combo amplifier' means an amplifier that is meant for musical instruments which has its loudspeaker built-in. Combo instrument amplifiers practically always have a mains plug with safety earth, the ones for guitar are usually not ideal for a theremin, because the output from a theremin is a stronger signal than an electric guitar's element deliver, so that's why usually a keyboard amplifier is recommended. The tone controls on an amplifier are also used to shape the audible sound, and you have the waveform and brightness controls on the Etherwave to adjust the sound and a keyboard amp also often has a built in reverb, which can also add to a nice sound. So if the 'box with setting' has tone controls, play with those, reducing the high tones can make a 'too electronic' sound already better. But not having a good earth will compromise both sound as well as playability. 

One thing is that in the USA the power supply for the etherwave does have a plug for connecting it to safety ground, while the European one doesn't and so it is expected to get earthed by being connected to an amplifier which is. Using a long audio cable to an amplifier and draping it on the ground can also act as earthing when connection to safety ground is not available. 

Okay, yeah it does have 'PHONES' and 'AUDIO'. They are both maxijack so I assumed that wasn't for headphones, since I don't know any headphones with maxijack. Or an amplifier.

Anyway. From what I understand, it still is important to have it grounded. What I dont know is whether I am. I shall try to explain the setup in my beautiful, non-technical language.

So. The theremin itself is plugged into a powerstrip, by using a non-grounded cable. That powerstrip is in turn also plugged into a powerstrip with a cable that is, in fact, grounded. It has a metal pin at the top that seems to connect to another piece of metal on the other end. That powerstrip is connected to the wall, which I don't know has the grounded thing. There is a metal pin in the plug itself but the socket has three holes, yet, no pins of sorts.

My questions now are: Is it grounded, because somewhere along the way it had metal parts, or does the outlet (by that I mean the wall) need to have the metal?

Also, is it okay that I have it currently plugged in a powerstrip in another powerstrip? It is problematic that my house has close to no electrical outlets. This entire floor has 4 total. Which is great, when you have an electrical piano, vaccuum cleaner, pc, two monitors, printer, phone charger, consoles, theremin, routers and more all requiring electricity. Luckily I am moving soon.

If it currently isn't grounded, I am unsure how I'd achieve that seeing how the electrical socket at the wall doesn't seem to have any metal parts. You mentioned using a long audio cable to an amplifier. Sadly I do not have a long cable as of yet. But I get that that is of importance. The current setup is really temporary anyway. In two days I should have a microphone standard and hopefully something else with an amplifier as well so I can put it elsewhere, also allowing more options to plug into.

So in short: I try to get it grounded, but other than that I can try to mess around with the current amplifier a bit to see if I can alther the sound and that's about it? It'd be great if I had that violin-esque sound, as opposed to this... I don't know how to describe

Alright, it is a Plus after all , the regular large size stereo phono jacks were the standard for headphones before walkmans and other portable players came around. Most amplifiers meant for musical instruments do have regular size mono phono jack sockets as input(s).
From how I understand your setup, since at the end the extension cords are plugged into a mains socket without the safety earth metal things on the sides.
I'm also in a somewhat older house that doesn't have earthed sockets in most rooms and I'm using some extension cords to get a connection to mains power with safety ground to my instrument amplifiers, which is actually not recommended, but I think is ok as long the amount of power that goes through it remains low so there's no danger of something overheating along the cables/socket blocks. In the days of old MW radios and playing around with DIY germanium diode detectors, connecting the 'earth' socket to a central heating radiator or a metal water pipe was wat we used to do.

Whithout proper grounding there will instabilities and interferences that will impact and disturb the resulting sound which can make it sound rough, wobbly and harder to set/get a playable range. violin-esque sound and any resulting sound depend on a combination of a well set up (grounded) theremin, how waveformand brightness are adjusted, how the tone control settings on the amplifier are set, some instrument amplifiers are 'voiced' in a particular way and may also have a built-in reverb wich can also improve the sound, while loudspeakers may also have their own characteristics. And last but not least an iportant part of the sound is in your hands, the precise characteristics how you move, of which some will improve through practice, there's also something that is related to and as characteristic as on's handwriting. Something I long ago learned from the manual of my old modular synthesizer is that it helps to emulate the sound a a particular instrument when you combine really listening to and studying the sounds of the actual instrument being played and while you are playing to envision and feel like you are playing the instrument you are trying to sound like. I feel that the same approach is also valid for the theremin.