After upgrading Ubuntu to 14.04 I had two problems.
– No sound from Spotify via webbrowser anymore.
Solved by: Installing pulseaudio-module-jack (4.0-0ubuntu11). This caused my PulseAudio JACK Sink to be available again. In PulseAudio Volume Control I then had to set the ALSA plug-in (under tab Afspelen/Play) to Jack sink.
– No connection anymore between my midi keyboard and the Jack Mixer. I could not control the volume in Jack Mixer via my keyboard anymore. The connection was visible in the JACK Audio Connection Kit via Patchbay (loaded via my patchbay configuration file patchbaydefault.xml), but did not get propagated to my connections in the JACK Audio Connection Kit. This was caused by a change in the name of the plug for my midi keyboard. Probably due to some previous re-installing.