Old Guy: the 515/416 are hi-fi speakers, the 421 is a MI. The 515 & 416 should beat the 421 in terms of reaching down to the lows, but the 421 can handle way more power, I think Altec rates the 421 at 150 watts, and the 515 & 416 at 75 watts?

voice of the theater: I wasn't there to see the actual "pyro-techniques," I was there only after the fact. There was a blacken grille clothe on the speaker where the center of the woofer, and my friend had to sheepishly explain to me that it caught on fire when he used to for his guitar.