I did some tests with Cache Enabler and it works great together with Autoptimize out of the box, especially after the latest release (1.1.0) which also hooks into AO’s autoptimize_action_cachepurged
action to clear Cache Enabler’s cache if AO’s get purged (to avoid having pages in cache the refer to deleted autoptimized CSS/ JS-files).
Just not sure I agree with this text on the plugin’s settings page;
Avoid […] concatenation of your assets to benefit from parallelism of HTTP/2.
because based on previous tests by smarter people than me concatenation of assets can still make (a lot of) sense, even when on HTTP/2 :-)