- ADPCM playback notes

  Each ADPCM format maxes out at just under a specific limit.
  If you attempt to play at the limit or faster, the decoded audio exhibits
  jitter/artifact noise as if the DSP has signalled an output rate faster than
  it decode.

  Note that the maximum discovered is almost DOUBLE in some cases the maximum
  listed in Creative's official documentation.

  4-bit ADPCM:                          Maximum just under 20KHz
  2.6-bit ADPCM:                        Maximum just under 19KHz
  2-bit ADPCM:                          Maximum just under 24KHz

- Testing notes:

  The card was tested twice.

  The first time, 8-bit PCM was played through an 8-bit DMA channel,
  and 16-bit PCM was played through a 16-bit DMA channel.

  The second time, the card was configured (ISA PnP) so that both
  8 and 16 bit PCM were played over an 8-bit DMA channel.