There should be a switch on there that allows you to run either channel independently or sum the 2 channels together. The eq's can be selected to affect either channel or both as well. I don't think you need the footswitch to do the switching but I'm not sure on that. The Carvin amps I've had, had little push-button switches to control all the features in addition to the footswitch used for switching "on-the-fly", while you're playing.
In order to get the most out of the amp I'd start like this.......
If you have an active bass, set all the tone controls to neutral and leave them there so as to not interact/interfere with all the amps eq.
Start by selecting channel one onoy and switching the graphic eq to "off".
You should then have a "basic amp" with 3 tone controls though all of those controls have semi-parametric sweeps. So, sweep through the bass control and find a spot that your cabs can reproduce well without sending the cones flapping for boosting. One could also turn that sweep all the way down for cutting rumble or taking stress off your speakers.
Then set the mid control to boost and sweep through all the frequencies. Then set it to cut and sweep through again. Lots of tone options there.
Then I'd sweep thrpugh the treble parametric and find a spot close to the topend of what your speakers can produce. This would be set lower if your cab does not have a tweeter, maybe higher if it does.
Then switch the graphic to "on" on channel 1 and you have more eq options piled on top of the knob tone controls.
Then you could switch the amp to channel 2 and basically have the same thing. The graphic can also be set to affect either channel or both.
The idea being you could set up 2 different sounds on the 2 separate channels and switch between them with the footswitch. Say one setup for fingerstyle and one for slap. Or you could set them for use with 2 different basses if you use different basses for different songs. Or you coukd set up ine tone with the knob controls and then switch the graphic on and off for a different sound. Or you could use the knobs to set your tone and set the graphic to affect both channels and use it to correct for the room you're playing in, etc. Lots of options there.
You can also combine the 2 channels for even more tone adjustment options.
That's the basic idea. One thing to watch out for with all those options is ending up double boosting or double cutting. For example, if you have the midsweep knob set to a 250hz boost and also push up the 250 band on the graphic, you've got a double boost happening at that frequency which will make it stand out a lot louder than the rest of your sound.
Or lets say you boost at 250 on the graphic but have a midsweep knob set to a cut at 250, those 2 would sort of cancel each other out and it'd be as if you didn't make any adjustments at all.
Throw an active bass in the mix and there's even more opportunity for that stuff to happen. If it happens to sound nice that way, fine, but watch out for double boosting in the bass region as that can be very stressfull in your speakers.
I used to have a PB-500 which came out after this amp. It was laid out a bit differently but shared some similair features. It can be confusing at first but I always thought that was a really nice amp. It was much better, fuller, beefier than the redline series which followed it. I had one of those too, but preferred the PB500 and sometimes wish I still had it.
It is good down to 2 ohms, so up to two 4ohm cabinets or four 8ohm cabinets. The thing would work really nice with a herd of small 8ohm cabs like 115's, 112's or 210's. Could basically scale the rig from a very small convenient little thing up to a big 4 cab stack depending on the gig.