Well over a hundred hours. Got it July 30th. It's been running 80 percent of the time. I've been out recovering from surgery since June 29th. Listening maybe 4-6 hours a day. It's sound is captivating. It will draw you in. I found myself listening to the same CD twice in a row many times. The sound just makes listening pleasurable. I tried some badly made discs and even though it didn't transform them it took a large part of the stridency out. An example of some great discs are Victory at Sea by Telarc is awesome. The Theme from Shaft (80s version) is also superb.