CAJUN ACCORDION DISCUSSION GROUP
if you just want to change key and not speed,
some guitar and studio effect boxes will do
i use the boss dr-50 multieffect that
i use on stage for key changing.
it also does, chorus, phaser,
reverb, distortion, fake 'wet tuning',
hammond organ effects, 'doubling',
fake lower octave for cheap chinese
you would think that if it changed key,
you could also feed your c accordion in there
and have it come out in a-flat or d,
but you would be wrong!
it does do that, but the key changed sound
is not very good, plus the acoustic
sound of the accordion will still be in c.
I use the Winamp player on my PC (link above), along with the plug in "Slow Me Down". There is also a plugin called "Take It Easy" with the same functionality.It does the same job as Amazing Slowdowner, but it's freeware.