Hey fireberd, thanks for the reply. I did manage to get the driver to work once again ! It sure is fiddly though and really shouldn't have to be done. Heres a copy and paste in a related thread I started in the Sonar section of the forum, on the lookout for a replacement controller in the event I could not get it to work again.
- in the last few minutes I have managed to get the old Edirol Win 8.1 driver and the PCR working on my Windows 10 Professional 64-bit system once again ! The difference this time, was finding out how to access hidden troubleshoot options on Win 10 anniversary edition via a <cntr> restart...once I could do this, I could disable driver verification, amend the install batch file from 8.1 to 10 and.....well my PCR lives to tell the tale once again, despite being stranded at 8.1 by Roland....
If anyone else drops by this thread in the future - this was the link that cracked it for me.
http://www.howtogeek.com/167723/how-to-disable-driver-signature-verification-on-64-bit-windows-8.1-so-that-you-can-install-unsigned-drivers/ Don't forget, visit the thread also to learn how to change the install batch file to change references from Win 8.1 (The last version of the PCR driver produced by Roland) to 10
Hope this helps anyone else...