Listening on a Stereo System

You do not need a multichannel loudspeaker array to use s3g-dsp. Keep each multichannel or ambisonic signal at its required width while it is being processed, then convert it to two channels at the end of the monitoring chain.

Keep the Session Wide

This refers to REAPER track and routing channel counts, not a single channel-count setting for the whole project. Each REAPER track has its own Track channels value, and one project can contain tracks with different widths.

For ordinary multichannel audio, set every source, processor, and bus track to at least the number of lanes the signal requires. An eight-channel chain needs eight track channels through the last wide processor.
For ambisonics, preserve every channel in the field: first order requires 4 channels, second order 9, and third order 16. Tracks and sends carrying the field must pass the complete channel range.
Place the stereo mixdown or decoder after the wide processing. The track can remain wide for the upstream chain; route the plugin's stereo output on channels 1–2 to the stereo master or hardware output.

Choose by signal format, not channel count. Use Output Autogain Stereo for ordinary multichannel lanes. Use an Ambi Decoder Stereo or Ambi Decoder Head when the channels are an encoded ACN/SN3D field.

Choose the Stereo Path

Signal before the stereo stage	Listening target	Use
Ordinary multichannel lanes or speaker feeds	Stereo loudspeakers or headphones	Output Autogain Stereo
`ACN/SN3D` ambisonics	Stereo loudspeakers or a stereo render	Ambi Decoder Stereo
`ACN/SN3D` ambisonics	Headphones	Ambi Decoder Head in `Binaural` mode
`ACN/SN3D` ambisonics	A carefully positioned stereo loudspeaker pair	Ambi Decoder Head in optional `Transaural` mode

A wide bus is not necessarily ambisonic. Ordinary lanes contain separate audio signals; ambisonic channels contain components of one encoded spatial field. The correct two-channel stage depends on that distinction.

Ordinary Multichannel Sessions

s3g Output Autogain Stereo accepts as many as 128 ordinary input channels and folds them into a true stereo output. Its layout, rotation, width, weighting, distance, attenuation, and autogain controls determine how the lanes reach the left and right channels.

ordinary multichannel source
-> multichannel effects, panning, or routing
-> Output Autogain Stereo
-> stereo loudspeakers or headphones

This is the appropriate path for discrete processor outputs, direct speaker feeds, and other non-ambisonic buses. It is a controlled mixdown, not an ambisonic decoder.

Ambisonic Sessions

Do not sum ambisonic channels as if they were independent stems. Keep the complete ACN/SN3D field intact through its encoders, effects, and utilities, then decode it at the listening destination. Set the decoder to the same active order as the field.

ambisonic encoder or instrument
-> optional ambisonic effects and utilities
-> Ambi Decoder Stereo -> stereo loudspeakers or stereo render

or

ambisonic encoder or instrument
-> optional ambisonic effects and utilities
-> Ambi Decoder Head -> headphones

Ambi Decoder Stereo uses virtual speaker fields and stereo pickup models. It is the normal choice for two loudspeakers and conventional stereo renders.

Ambi Decoder Head uses a synthetic head model. Choose Binaural for headphones. Its Transaural mode adds crosstalk cancellation for stereo loudspeakers, but the result depends strongly on speaker angle, a centered listening position, and room acoustics.

REAPER Setup

Open the routing controls for each wide source, processor, bus, or monitoring track and set Track channels to the required width. There is no project-wide channel count to set.
Check that sends between wide tracks pass the complete source channel range to the same destination channels.
Place the chosen mixdown or decoder after the processing that needs the wide bus.
Map its left and right outputs to channels 1-2 and then to the stereo hardware output.
If a following meter still shows higher channels, open the plugin pin connector and enable Zero out unmapped output channels.

Output Autogain Stereo, Ambi Decoder Stereo, and Ambi Decoder Head expose true stereo output buses. REAPER can nevertheless preserve unmapped higher track channels around a plugin unless that pin-connector option is enabled.

What Stereo Preserves

A two-channel monitor preserves a useful left-right image, balance, motion, and much of the spatial character needed for composition and auditioning. It cannot reproduce the physical coverage of a surrounding loudspeaker array. Treat the stereo path as a valid listening destination and monitoring format, while recognizing that a later array decode may reveal height, rear placement, and envelopment differently.