#1
Bass amps require a higher wattage than guitar amps to achieve a similar volume/sound in general.

if so why and to what degree?
#2
Yes, they do. It's because of the way the lower frequencies travel or something of the sort.

To what degree? I've heard there's a rough rule before, like the bassist would want around 2x what the guitarist has...can't quite remember.
#3
Thanks alot, I'll bear that in mind when i buy an amp.

EDIT: If anyone does know the aforementioned rule, please post.
#4
It all has to with speakers, almost all speakers are not very efficient at Freqences below 100-80hz, since bass gutars primaly play between 40-100hz, you see how this can be a problem. Subwoofers, and loudspeakers used in bass cabs and amp are typically 90-95 db 1watt@1Metter, 40-500hz and typically guitar speakers are 97-102 dbw/1watt@1 meter, 70-5000hz so you have a big volume difference right at the start. But honestly if your wanting a decent bass amp look for somthing with 150-300+ watts if your going to be giging, 300-Plus without PA subwoofers, with soild state amplification. With a bass tube amp I would recomend 100-200 watts, that should really suit you well in most situations.