Some Speakers questions


I have a question, would good SPEAKER SYSTEMS be better to use for amplifying my instruments (guitar bass etc.). The only cool thing im finding in normal guitar/bass amplifiers is that it comes with effects. Do some speaker systems have the same capability as amps? What is a subwoofer? Is that bass speakers? What can I use to amplify my instruments OTHER than normal instrument amplifiers? I want quality sound, and expandibility/compatibility (I would be able to play guitar on it, and also be able to play bass on it and still have good bassy sound)
Sorry I couldn't really state my questions more clearly.


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