epat

Simply put, there is no comparable alternative to JACK if you want sound in linux. The ablity to connect any audio input with any audio output is not unique, but the in built mixing capabilities and low latency design makes this top notch sound system even better. Add to that, the range of quality programs dependent on JACK and those that support it and you've got a whole treasure trove of amazing sound production and effects processing facilities on your linux box - all open source of course!
~epat. :)

Ardour is the best digital multitrack audio mixing/mastering software that open source has to offer and is a very capable application. Although some features are lacking at present, new projects and innovations should bring MIDI support as well as just plain audio which will probably make this the best sequencer software around as well. The features that aren't lacking are very complete and well thought out and development seems to be attracting more attention gradually. The UI is the best part though, the dark interface, utilising a very nice colour sceme and icons coupled with the clearlooks GTK theme, does not make your eyes tired with prolonged use and is very fast and accesible. The workflow is very fast, although it can be tricky to learn what keys do what for instance and sometimes a mouse alternative doesn't seem obvious. All in all, it's an excellent program and looks set to dominate the open source and linux audio front in 5-10 years if development continues! Brilliant! 5 out of 5!!
~epat. :)