Concert: 3-band EQ (treble/mid/bass), 1st generation rated 150 WRMS @ 4 Ohm also featured Distortion and Boost (need remote pedal to function). Pretty good sounding bass amp w/ JBL. 2nd generation rated 200 WRMS (larger heat sink), but did not have the Dist/Boost features... which can be fun to utilize occasionally... making the 2nd genreation head a little more traditional (and less fun). Lifting the hi-pass filter cap on the brite input pre-amp circuit board allows for using both inputs simultaneously without the loss of low end.
Coliseum: 4-band EQ (treble/mid/hi bass/lo bass) with Q shift point switches on mid/treble bands. Very flexible tone circuit, very powerful amp (300 WRMS @ 2 Ohms). No brite input jack, so you can use both inputs simultaneously without the loss of low end... a useful feature for me since I frequently plug my bass synth set-up into my bass amp.