None of them..

Ketron never replaces instruments but allways adds more instruments to their collection....old instruments only leave their offerings when out of stock..

where the SD40, is the SD7's arranger
the SD90 is the SD9 pro's arranger.

i think the SD9 is their current top of the line arranger.
Where the Audya is their older top of the line arranger.

they will not say at Ketron that the SD9 is the replacement of the Audya as long as they have audya's in stock...

SD9 vs SD7
-launchpad feature
-Possible future sampler
-More sounds
-sample memmory
-More DSP
-More advanced audio styles with live guitars and such

SD90 vs SD40
-More accesible interface
-larger and 3.5kg vs 2 kg


Audya vs SD9
-I would love to know what features the Audya has to offer that are not on the SD9 series..