It is possible for an ASIO device to soecify different sample formats for different audio channels (for example a device may have 24 bit analog i/o and 16 bit SPDIF i/o).

PortAudio currently assumes that all channel sample formats are the same as the first channel. This is a reasonable assumption for most but not all hardware. Need to find hardware that does have multiple sample formats to test this.

Fixing this may require the block processor to maintain per-channel conversion functions - could get nasty.