What it needs
The M8 reads 16 bit PCM WAV at 44.1 kHz, mono or stereo. Current firmware also accepts 8, 24 and 32 bit files, so this is the target rather than the limit.
Dirtywave recommends 16 bit for performance, which is the useful framing. The machine will play a 32 bit file, and a tracker running many voices is not where you want to spend the headroom.
Format WAV Sample rate 44.1 kHz Bit depth 16 bit Channels Mono or stereo
Getting the files there
Samples live on the SD card and the M8 browses the card directly, so preparing a folder on the desktop and copying it across is the whole workflow.
Prepared folder on disk
Kick 01.wav 44.1 kHz 16 bit
Snare 03.wav 44.1 kHz 16 bit
-> SD card
-> browsed on the M8
Doing it in Sample Miner
Export Options has a Hardware target dropdown. Selecting Dirtywave M8 sets WAV at 44.1 kHz and 16 bit, leaves the channel count alone and clears the sampler format.
Because the M8 browses the card, the folder structure you export is the structure you navigate on the device. Naming the export folder well is worth the few seconds.
The limits
Renders come back at 44.1 kHz as 16 or 32 bit, so a round trip through the M8 lands on its rate rather than yours. Plan the project rate around that rather than fighting it.
The M8 is a tracker, so what it wants from a sample library is breadth of individual sounds rather than mapped instruments. Multisamples do not arrive as one object.
Sources
Specification confirmed against the Dirtywave M8 manual.
Other devices: Digitakt, SP-404 MKII, Model:Samples, Lofi-12 XT, EP-133 K.O. II.
What the files themselves contain is in the format reference, and the words each sampler uses are in the glossary.
To check a file you already have, drop it into the file inspector. It runs in the browser and uploads nothing.