Digital
DSD rate ceiling
When an input accepts DSD, but at a lower maximum rate than the source can send.
Simple
DSD comes in speed grades — DSD64, DSD128, DSD256 and up. If your source can send a faster grade than the input accepts, those few files get converted or played at a lower rate. Regular PCM playback isn't affected at all.
The theory
DSD rates are multiples of 2.8224 MHz (64× the CD sample rate). A rate mismatch isn't a compatibility failure: players transcode DSD to PCM or down-rate it transparently, and DSD-over-PCM (DoP) framing needs 176.4 kHz of PCM bandwidth per DSD64 stream — which is why TOSLINK, capped near 96 kHz, can't carry even DoP DSD64 reliably while USB carries DSD512 natively.
For experts
The engine notes the ceiling as info because the practical impact is a format conversion, not a broken link — and because the audible difference between native DSD256 and a competent DSD→PCM transcode has never survived controlled comparison. If native DSD playback matters to your library, the note tells you which connection preserves it (usually async USB); if it doesn't, the note is safely ignorable.