PCMSTREAM plays WAV files with 16 bit signed samples, but the microphone and both WAV players use 8 bit unsigned samples.
here's a command to convert 8 bit -> 16 bit signed:
ARYOP #AOPMAD,NEWWAV%,OLDWAV%,256,-32768
it multiplies each sample by 256 and subtracts -32768
(I bet this is why they added the multiply-add option for ARYOP)
example program:
DIM I%[0] LOAD "DAT:TEST.WAV",I%,0 DIM O%[LEN(I%)] ARYOP #AOPMAD,O%,I%,256,-32768 PCMSTREAM O%,rate(for most old WAV files, the rate will be 8180Hz, but some use 16360 or 32720 (or very rarely: 16162 or 10910)