Two Small Amps = One Big Amp?
If you have experience playing on the bandstand, then you know how important it is to have enough volume coming from your amp to be able to hear yourself... If you can't hear yourself, you can't play. Usually the answer is to use a big amp, like the Fender Bassman (4x10" speakers). Another way to go about it is to use two smaller amps. If you want variance in tone, bring two small amps that sound very different... one clean and one distorted. The clean one usually helps you to hear better and the distorted one is the one usually mic'd into the house system. You could use the two amps side-by-side... or one stacked on another... or one in back (on a chair) and one in front of you, tilted back like a monitor!
To chain them together you'll commonly use an A/B box (foot pedal on the floor), though you could use a simple splitter (one 1/4" female for the mic to 2x1/4" male to go into each amp).
Two Fender Super Champ X2's sound great... I've used two of these amps with very good results.