When using the Output Options Mode for Combo Front & Stack Front, there are 3 additional options...Focus, Lows, Highs.  The factory default setting for the lows is -49, Highs -50.  These 2 settings absolutely kill the low and high tone!  I've now set both low and high to "flat"...sounds good now.  I use the combo front option, using the 1/4" output jack to various combo amps I own.  Discovered it when selecting the tuner and it happened to have the "bypass" option 2 selected (default from the factory).  I've seen very little discussion about this tone killing default factory setting.  The other option, Focus, varies the mid frequency from 100hz-2.5khz.  Default is 570Hz.  Book says it "increases the overall midrange".  Playing with that also affects the mid tone quite a bit...so far I'm leaving it at 570hz.  This Focus control may be good for optimizing the mid tone when using various combo amps.