A number of people on this site have described various heads as 'flat'.... Acoustic Image, Walter Woods, iAmp800. I am lucky enough to have owned all three of these wonderful heads at one time (Clarus, Ultra, and 800)... and each amp, using the same speaker (Epifani410UL) and the same basses (MTD535, Rob AllenMB2, Lakland 94-55, among others) sound VERY different set 'flat'. So.... does 'flat' exist? My opinion is that a 'flat' amp is defined by most players as a head that sounds good (to them!) with the tone controls not engaged or set at unity. So..... what is 'flat'!!!!!???!!!!