In most circumstances, I would not use the Front Bypass mode unless you are advanced enough to have set up your front speakers perfectly, or prefer 2 channel music as Peng suggested above. Also, unless you have an unusually dead and.or overly treated room, the recommendation would be to use Audyssey Reference over Audyssey Flat. Audyssey Reference is the default because Audyssey feels this is what most people should use in most situations.