"230 =2004 model 6.1 only, need seperate amp for 7.1
235 = 2005 model adds 7.1, A/V synch delay adjustment, heaviest of the 3, adds Dolby PLIIx
240 = 2006 model adds iPod bridge and assignable component inputs, naming video inputs
330 = 7.1, can assign surround back channels for multi room
335...