There is a version of this piece that plays through a real surround system: every star is sent to the speakers it actually sits between, and the sky turns around the room instead of around your head. It is the closest the piece gets to what it is meant to be.
It takes some setting up, and most of that setting up is in your computer and your receiver rather than here. This page walks through it once. You should only have to do it once.
Connect the computer directly to the receiver. Going through a television is the obvious thing to try and it usually fails: many televisions will only pass two channels back out to a receiver, whatever comes in. If the sound has to pass through a TV on its way, expect stereo.
This is the step everyone skips, and skipping it is why the piece plays in stereo and nothing warns you. A computer assumes two speakers until you tell it otherwise, even when the receiver on the other end of the cable is perfectly capable.
First, turn the receiver on and select the input the computer is plugged into. The computer only sees the receiver while it is powered on and listening. With it off, the whole output device disappears from your sound settings, which looks exactly like "my computer cannot do this" and is not that.
On Windows: open Sound settings, find the HDMI output device, and open its properties. Turn spatial sound off. That feature adds its own imitation of surround for headphones, and over real speakers it fights what the piece is doing. Turn off any enhancements, loudness equalisation or bass boost while you are there. Then choose Configure and pick 5.1 Surround (or 7.1), and run the test tones. Each speaker should sound in turn. If 5.1 is not offered at all, the receiver is not telling the computer it can accept it, and no setting in the piece will change that.
On a Mac: open Audio MIDI Setup, select the HDMI output, and use Configure Speakers to set it to a multichannel layout.
Expect it to be set to stereo when you first look. That is the normal starting state, not a sign that something is wrong.
Two settings matter.
Use a sound mode that passes the channels through untouched. Receivers ship with modes that invent surround out of stereo, and those will happily do it to a signal that already is surround, smearing everything. Look for a mode described as direct, straight, or automatic decoding. On the Sony receiver this was developed on it is called A.F.D. Auto. Avoid anything that says it is expanding, upmixing or filling.
Set your front speakers to "small", with the crossover at 80 Hz. This sounds like a downgrade and is the opposite. The Moon in this piece is a 36 Hz tone with a 72 Hz tone above it, lower than most speakers can physically produce. Set to "large", your receiver sends those tones to the front speakers anyway, which then move a great deal trying to make a sound they cannot make. You lose the bottom of the piece, and the straining shows up as faint pitches that are not in the composition at all. Set to "small", the receiver sends them to the subwoofer, where they belong.
On your phone or tablet, open the app, tap surround, then get my code. Send the link to the computer (AirDrop, a message, or an email to yourself) and open it there. If sending is awkward, go to theuntemperedcosmos.com/unlock on the computer and type the six words instead.
You only do this once for each browser. The unlock is remembered, and the piece opens in surround from then on.
Open the piece on the computer. It reads how many speakers your computer says it has and uses all of them. A listening on control appears under the begin button, so you can switch between surround speakers and headphones. It remembers your choice.
If the computer reports only two speakers, the piece plays the ordinary version and says so under the stop button. That nearly always means the computer is still set to stereo. See "Tell your computer it has surround speakers" above. Even when it does play in surround, it is worth checking, as the section after next explains.
A phone knows which way it is pointing. A room does not, and neither does a laptop, so the piece has to be told once: which compass direction are you facing when you look at the front speakers? Aim at the centre speaker if you have one, or the middle of the front pair if you don't.
Your phone's compass can tell you, to the degree. Sit in your listening seat, hold the phone flat, and point its top at the front. Type the number it shows (273, say) into the control under the stop button. Two cautions:
No reading to hand? South is a sensible starting guess in the northern hemisphere, because that is where the Sun, Moon and planets cross the sky. It puts the loudest, most-moving voices across the front of the room rather than behind the sofa. South of the equator, north.
You can change it while the piece is playing and hear the whole sky rotate to match. Type a new number, or use the up and down arrow keys to nudge it a degree at a time (hold shift for ten degrees). It is remembered afterwards.
This is worth doing, because the failure is silent and convincing.
"The sound moved around the room" proves nothing. A receiver making fake surround out of two channels produces exactly that impression. Two things actually settle it:
Your receiver's channel display will not help here, and it is worth knowing why before you trust it. Once you have told your computer it has 5.1 speakers, it sends six channels down the cable all the time, even for a web page playing plain stereo, which simply leaves four of them empty. The display reports what is arriving, not what is being used, so it will read 5.1 either way. It is a good check that your cable and your computer are set up correctly, and no check at all on whether you are hearing the surround version.
If it is playing in stereo, go back to the second section. Nearly always the computer is still set to two speakers, or the receiver was powered off when you configured it.
Judge this piece's bass on speakers, never on headphones. Most earbuds roll off below about 40 Hz, which is precisely where the Moon lives, so headphones hide the lowest voice in the piece almost entirely, while a room with a subwoofer does the opposite and adds to it. The two can sound like different pieces minutes apart. The room is telling the truth.
Set your levels before anyone sits down, and then leave the volume alone while the piece plays. Changing volume mid-piece can make some receivers renegotiate the HDMI connection, which drops the sound for a couple of seconds.