In addition to what's in the New MC15 Features sticky thread there have been some other changes that benefit audio only use as well. I don't know everything that's changed. A biggie for me though has been improved VST effect support. I like to play with EQs and use a couple of VST EQs. VST support is better in MC15 than MC14. There's also been some improvements in the WASAPI Event Style mode that is a big benefit to some folks with some fancy (expensive) DACs and not so fancy DACs. There's been other changes and improvements to the audio pipeline and processing as well in MC15.
I use MC15 almost exclusively for audio. I find it worth the upgrade for my use. The audio only users weren't ignored in this upgrade.
