Finding out that Reaper 4.14 (whether 32-bit or x64-bit version) works with Jamstix 3.30 (another latest release) on Windows 7 64-bit, only completely when Run As Administrator is checked for Reaper.
Without Administrator privileges, Jamstix produced MIDI output, but was unable to load its own sound engine and stayed silent (though if routed to EZDrummer, you could hear the drums fine).
Still evaluating the merits of running 32-bit DAW’s (shown below – more VSTi’s recognized):
Versus 64-bit Reaper:
In both cases, I’m testing sending a 2nd MIDI stream from Jamstix to drive the EZDrummer track (to use the EZD sound kits).
Reaper is available at www.reaper.fm
Jamstix is available at www.rayzoon.com