Whats the difference between getting a ~$200 attenuator vs using a ~$10 L-pad, especially on lower power amps? (in the neighborhood of 5w-15w)

All I can gather is that attenuators use a bank of sand resistors and an L-pad is just a double rheostat that sweeps through resistances. Any difference in function or sound? I'm just trying to get a 5w tube amp down to levels that will be in overdrive range, but not piss off my roommates.