Hi..
 >  MB>>> afaik, sbpro has 1-left 1-right input, and 1-left 1-right output.
 >  MB>>> that's what i've been hearing for years, literally.
 >  RL>> Well.. that makes 4 channels total.. I guess that must be it.  Thx 
for
 >  MB> but, on the SB, you can't input and output at the same time (& that's
 >  MB> pretty bad imho)
 > Well, on my SB16 that seems to be no problem... I can input any signal
 > into the SB, record it as a WAV for example, and at the same time the
 > amplifier picks up the signal from the SB-output, so that I may hear
 > what is recorded.
This action is performed in the card's hardware, and is operational ALL the 
time (not just when recording) - go to the SB's volume control tool, activate 
and turn up the volume for the microphone. Now, talk into the mic -- you'll
hear yourself! Most of the time the mic's volume is set to 0 so this 'effect'
doesn't cause feedback (a high pitched whistle you get if you put the mic too 
close to the speaker). Remember this is a HARDWARE feature, not a software 
record-process-playback loop.
 > Maybe this wasn't working on older SB-Pro's, but on the newer SB-models
 > it does! Or is that something completely different from what you mean?
What he meant was the ability to simultaneously record and play back. for 
example, record your voice and at the SAME time play a _different_ WAV. This 
can only happen with cards that have TWO DMA channels... the SB16 series 
don't have this feature. You can 'fake' simultaneous record-playback by doing 
the following:
loop:
  enter_record_mode
  record_one_byte
(  Process_one_byte_if_required  )
  enter_playback_mode
  play_one_byte
goto loop
But it's very crude, and the top sampling rate is reduced to somewhat less 
than 50%. not recommended!
    Craig
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