Do you already have your front high speakers connected?
If so, try this. Go to speaker settings 2-1 and set front high/wide to "No" Now go to speaker configuration 2-2 and set your crossover point. Now go to 2-4 Level Calibration and scroll down to front high L/R. You should have front highs now.
Remember those speakers will only output sound when used with these listening modes:
DTS Neo:X (Cinema/Music/Game), DTS Neo:X Cinema + THX Cinema, DTS Neo:X Music + THX Music, DTS Neo:X Game + THX Games, Audyssey DSX (PLII + Audyssey DSX included), Orchestra, Unplugged, Studio- Mix, TV Logic, Game-RPG, Game-Action, Game-Rock, Game-Sports, All Ch Stereo, Full Mono