klipsch speakers

If all you are interested in is loud, buy him some Cerwin vegas.  Most klipsch speakers (especially heritage) are too high quality for what you propose. IOW, you would be wasting them on such a chore. Keep in mind that a pair of fortes or klipschorn will beat most contenders in their respective categories even today.
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I agree with Ozzy. If volume is all that matters, Cerwin Vegas will fit the bill nicely, probably on the cheap as well. While Klipsch can certainly play loud, they are a more "musical" speaker that I have a certain reverence for. Certainly, if you could find a Craiglist bargain, go for it. Klipsch (depending on the model) will reward him with volume and fidelity...

Izzy is spot on. Cerwins are loud and cheap. He’s really not deserving of kliosch speakers. 

I favor Klipsch (horned) for low power amps bcos they have excellent sensitivity...

Younger people like bass, get a 14" SVS sub and some cheapish full range floor standers and they'll be happy.

He would dig Cerwin  Vegas....big 12 drivers....nice