I am going to disagree with you. If you move the bars to the top you have the same signal as EQ off ONLY for the frequencies that those few bars control . You leave all the other frequencies at 6 dB below the now boosted frequencies and you end up with a mess. The sliders control frequencies centered at the few points selected. Sure, it smooths out some but it is not "the same". The 6 dB drop is just plain not worth doing. Just don't max out the amp when using the tone controls. Doh!
And I will respectfully disagree. By pegging all the sliders to the max and then switching between CUSTOM and OFF I hear zero difference. I better get my hearing checked for the missing non-boosted frequencies.
"You" don't hear a difference. Well that works for "You" and who else? 5 band EQ and 10 band EQ systems only control the frequencies they center on, leaving the rest to fade to each side. Your ears don't notice this, but it still happens. Lots of people say "they" don't hear a difference between mp3s and FLACs. "You" do, right?