I'm setting to STEREO. The switch is *not* set to BYPASS. Yes, if it was set to BYPASS then as Scott says, it would alway pass the full frequency range to the front speakers. But it's not set to BYPASS in this case. The front speakers are set as small. Yet I hear the full frequency range, unaffected by the crossover setting. I've switched the crossover setting from 40 to 150 Hz and I hear no difference.

Has anybody else had the chance to try this, with your subwoofer physically turned off?