Ardour V4.0 runs on Linux, OSx and now Windows and no longer requires JACK.
While the option to use Jack continues on all platforms, Ardour now directly supports,
- ALSA (Linux only)
- ASIO (Windows only)
- CoreAudio (OS X only)
There has also been a complete user interface modernisation which means that Ardour 3 themes are no longer supported.
Additionally there has been a significant improvement in memory management with empty session memory use reduced by 80%.
More details online.