Hmmm - your sound is being sent FROM the Laptop into a DI then into the speakers? If so, you don't really need the DI (impedance matters, but not so much in the level/distance you're trying).
Your laptop output (line level signal - like a CD player? or are you using the headphone out?) might be weak in any case, so you need boost from a true power amp. Any power amp will work...
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Relax and float downstream...