You'd have to figure out the time it took for the electricity to travel from your keyboard to your computer and to have your computer recognize it and have stepmania realize it and then hit just that far early. An easier way to get an "exact" would be to make a song with something random like easy but fast rolls. That way you'd go offsync a little bit and hopefully get one or two of them.
no i remember a thread a while back where people were posting scores.. and somehow in sm you can go into a file and it shows how off you were hitting a note on any given song you played.. and moogy posted one that was 0.0000 i think.
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