I’ve tried the M-Scaler with every DAC that has come through my hands since it arrived.
How well that works depends greatly on how the DAC you’re feeding from it handles higher-rate input signals, and what it can accept from a single BNC (COAX with a cheap adapter) or TOSLINK connection.
It is definitely at its best with Chord’s DAC supporting dual-BNC (705.6/768 kHz) input (DAVE, Hugo TT2, Hugo 2, Qutest). To the point that I am not sure I’d go back to them without it.
It negatively affects my perception of Schiit’s Yggdrasil Analog 2. Was surprisingly positive with the RME ADI-2 DAC FS (original, not tried it yet with the 4493 version). And didn’t do anything useful for most of the PCM-mode chip-based DACs I’ve tried recently.
It’s been largely positive with NOS DACs (for hopefully obvious reasons).
But, in general, it’s much more interesting with Chord DACs capable of dual-digital input.