Karl DL wrote, red boards look more "contemporary", green are "retro" my old stratos got the red board treatment when it was matched to a new, second unit recently. curiosity got the better of me, so i opened it up and went looking for changes. the drivers were changed(2SD17623A & 2SB1186A to 2SC4793 & 2SA1837) pre drivers changed (2SA1124 & 2SC2482 to 2SC4793 & 2SA1837) and the operating point of the input stage was changed (quiescent collector currents increased by a factor of 250 %) the drivers base resistors were increased, which shifts the bias voltages around a little between driver and pre driver bias and offset potentiometers were changed from single turn to ten turns which makes thier adjustment much easier ( for Odyssey and us tweakers) not having red and green in the same space at the same time, i cant say anything comparatively about thier sonics. i was happy with the green and now i am happy with the red. Karl