You are right sk880user regarding the separate "virtual" volume sliders within the vocal harmony mixer. I would think that the main physical slider on the keyboard itself would be able to perform a global increase/decrease in mic/line input. It seems to only control the main input while the harmony voices remain the same volume. Regarding the quality of the vocal harmony I find it quite good for my purposes. The unison effect really helps my voice a lot as I have a soft almost folk/country style quality to my voice. Although when properly inspired I can cut loose and do some real in your face old time rock. The four-part harmony when use sparingly sounds very good to me. I've recorded just the harmony parts and they stand up by themselves quit nicely IMHO. It’s not a voice prism but I think it’s on a Digitech Vocalist level. Again, that is only my opinion. As they say, "your mileage may very".