Here are some apps that are cross platform such as Mac, Linux and PC. I has use these apps on several occasions and I feel that they can come in handy at some point. Ardour is equivalent to Samplitude, Sequoia, Protools, Nuendo, Digital Performer, Logic Audio and SonarX2/3 on the Linux platform. It also runs on Mac. I don’t know when the PC version will be available. Since Linux OS takes up very little CPU, you can build a powerful workstation and create to your heart’s content.
Audacity is an cross platform app to that allows you use VST audio plugins.