Hi,
Unfortunately, the ones you mentioned are possible solutions on how to get AD9959 to work on 64-bit OS and the AD9913 to work on 32-bit win7.
To the best of my knowledge, our AD9959 will not work on win8.1 64-bit. But I will have to refer this to the team if ever there are possible solutions or workaround on this.
For now, I found this helpful article regarding migration of cyusb drivers that will be compatible to win8.1
Migration of an EZ - USB® FX2LP™ Driver from CyUSB.sys to CyUSB3.sys – KBA92893 - Cypress
Hope this helps.
