No, I meant 38kHz. When in FM mode, the DSP runs at 38kHz which I believe is based on the way FM multiplex is transmitted (ie, 0->19kHz is L+R, 19->38kHz is L-R, allowing stereo separation to be performed).

The FM signal comes in as multiplex (which includes L, R and RDS data) into the DSP. We don't see it again until it comes out as sound - at 38kHz. We can't get it into the main CPU as the CPU is sample-rate locked at 44.1kHz. The ADC for the FM (and the DACs for audio out) are all inside the DSP.

The Mk2 allows 16-bit stereo sampling of the output at 22.05kHz, which is sufficient for most things.

Hugo