A
Of the new configurations, the “215x” models have six inputs and three outputs while the “315x” models have 10 inputs and four outputs. Model numbers ending with a “55” replace two HDMI inputs found in models ending in “50” and instead include two DXLink twisted pair inputs. Additionally, the “T” in the model number designates units with a 70/100V amplifier. “SP” models have an 8-ohm amplifier.
You can see all the details here: http://www.amx.com/products/categoryAllInOnePresentationSwitchers.asp