Up for sale is an excellent Apogee Duet 2, 2-In 4-out USB audio interface. The driver from Apogee still works in the latest version of OS X and can be downloaded from Apogee for free. https://apogeedigital.com/support/duet-2 Apogee has also announced the availability of Duet driver for Windows 10. https://apogeedigital.com/blog/windows-compatibility-one-duet-quartet This unit will work in both OS X and Windows 10.