My Denon subwoofer just died. Can I plug in a Bose acoustimass 5 series bass speaker in to the new receiver Denon AVR-1500H I just bought to replace the sub woofer? Can I plug it into the extra side speaker slots? Will it do what the subwoofer is supposed to do?
Probably not. You haven't provided enough information about the components but I'm guessing the Denon subwoofer contained other electronics that controlled the cut off frequency of the system. The Bose most likely does the same but it will be set up for the Bose speakers in the Acoustimass system. Generally, Bose works only with other Bose products and Bose is not compatible with any other brand.
I assume by "side speaker slots" you are referring to the additional surround speakers intended for multi-speaker surround. Those channels contain no bass frequencies.
Go to an audio shop - not a big box - and have them explain what you need and how much this will cost.