-05 has higher quality analog component video DAC.
-05 has touch capacitance controls vs. buttons on the 51
-05 has glossy black metal front plate (likely to enable touch cap.) vs. glossy black plastic front plate on the 51
-05 has gold plated rear terminals vs. standard terminals on the 51
-05 has primarily gold highlights vs. silver highlights on the 51
-05 has amber LED display vs. white LED display on the 51
-05 remote has...