the way the power supply switches to produce power, i read a little on it but my thinking class i is like class t which is a derivitive of class d =) kinda like a/b is now (not meaning a ,b or a/b are the same as class d just they call the combo of the 2 a/b and not somethin else like class v). hell elkhart is 60 minutes from me lol. but way i see it its a balanced current version of class d which would make it a lil more eff but also make it more accurate at all levels (like adding low tolerance components vs. high tolerance components in the same design of amp) i dont have any real lit on it other than the mag all amp topology books i have just cover a-d with a few others mixxed in...but again all the specs are just that our ears cant depict most of the numbers but they can tell the difference between a pioneer power booster eq vs. a zapco amp lol.