ATV Sound Check Question

When switching Sound Check off and then back on in Apple TV settings, I detect no difference in sound levels. I have tested this with Sound Check on and off in iTunes.

This isn't normal, is it? Is there a lag period in music playback on an ATV before sound check kicks in or out, depending on how the setting is changed?

I ask because doing this on an iPod brings instant change in sound levels. I also ask because I am a bit skeptical about Sound Check's effectiveness when playing music back on an ATV.

Thanks.