Hi guys. I have Audya 4 with a Kingston 120GB SSD and I agree that OS 5.4c is a disaster. The best OS version for Audya 4 is 5.3D. I have tested last three versions and these are the results:
Os 5.3d ----> boot time (with my samples) 2.58
Os 5.4b ----> boot time (with my samples) 3.20
Os 5.4c ----> boot time (with my samples) 3.20
OS 5.4c is very slow and it lags switching from style to style. I had also a problem playing wav files. While the song played suddenly it stopped. Another big problem relevant to OS 5.4c is that while I was playing live the system stopped responding, I could not do anything and I had to turn off Aydya 4 and open it again.
It is very disappointing from Ketron. Ketron must find a solution and test OS versions in depth.