I don't think you can display the perceived quality of a Hi-Fi on a graph! Accuracy perhaps, but one of the things you NEED to include is the effect the room has on the sound.

Things like prat... its not all down to the speed of the system (rise fall time, transient response, room decay rate) as I think things like frequency response subjectively effect this as well. How clear and un-distorted effect how 'fast' the brain perceives the sound to be; how easily it can tell what is going on. It's all just a gamble in the end but I think experienced designers / system builders can make an educated guess.

Its a bit quiet on here tonight isn't it?