It's been a while I was here, but anyway;
You don't need to buy any additional software if you use CPA 9.x
The only thing you have to do is load an instrument patch for the RA 90.
If you have to buy CPA 9.0 first, and you will just use it for playback the midi's, this is an expensive investment and indeed the alternative Fran offered is way cheaper.
But in case you have CPA 9,x or buy it anyway, you don't need any other software.
Fred
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Keyboards/Sound Units: Kurzweil 2600S, Roland VR-760, Acces Virus C, Roland G-800, Akai AX60, Minimoog, Machine Drum, Roland R8-M, mediastation x-76