I saw this on Massdrop. Mine is about 5 years old from Mayflower Electronics so should be as NwAvGuy intended as per his licensing agreement.
https://www.massdrop.com/buy/massdrop-o2-amplifier/talk/241801?mode=guest_open
https://www.massdrop.com/buy/massdrop-o2-amplifier/talk/241801?mode=guest_open