byuu says:

Changelog:

  - added all pre-requisite to make install rule (note: only for higan,
    icarus so far)
  - added SG-1000 emulation
  - added SC-3000 emulation (no keyboard support yet)
  - added MS graphics mode 1 emulation (SC-1000)
  - added MS graphics mode 2 emulation (F-16 Fighter)
  - improve Audio::process() to prevent a possible hang
  - higan: repeat monaural audio to both left+right speakers
  - icarus: add heuristics for importing MSX games (not emulated in
    higan yet in this WIP)
  - added DC bias removal filter [jsd1982]
  - improved Audio::Stream::reset() [jsd1982]

I was under the impression that the 20hz highpass filter would have
removed DC bias ... if not, then I don't know why I added that filter to
all of the emulation cores that have it. In any case, if anyone is up
for helping me out ... if we could analyze the output with and without
the DC bias filter to see if it's actually helping, then I'll enable it
if it is. To enable it, edit
higan/audio/stream.cpp::addDCRemovalFilter() and remove the return
statement at the top of the function.