At the 'Main' menu go to 'Options' and select the 'Cheats' option. Then at the 'Unlock Everything' menu enter the case sensitive code 'tol0' (without the quotes). This code cannot be used online and will disable high scores.
When you activate Euphoria ALL Crossfades and Spikes will be automatic (make sure you have the crossfade in the correct position when Euphoria ends). Euphoria is equivalent to Guitar Hero's Star Power, collected by successfully completing specific phrases in the song mix, called Perfect Regions, and can be released by pressing the Euphoria button, doubling the player's current multiplier.