The L420 is a great little speaker, but you should probably use a sub with it as the 6" woofer doesn't quite go low enough.
Most ADS speakers use a 1" tweeter (the 1290/1590 use a 3/4" tweeter), they use either a 1.5" or 2" midrange if the speaker uses one, and the woofers vary in size. Depending on the configuration, the bigger the woofer the lower they go and more power handling. Some, like the L718/810 and others use double woofers for increased power .handling
Most ADS speakers use a 1" tweeter (the 1290/1590 use a 3/4" tweeter), they use either a 1.5" or 2" midrange if the speaker uses one, and the woofers vary in size. Depending on the configuration, the bigger the woofer the lower they go and more power handling. Some, like the L718/810 and others use double woofers for increased power .handling