You'll be amazed by this small bar. They have concerts and jam sessions everyday: jazz, soul, rock, punk, latin... Check the program on their website and you won't be disappointed. Most of the concerts are free entry so the average price for a drink is a little bit high (but normal for the area).
Nice bands and musicians and a wide range of genres. Get there early or it might be crowded. The concerts are sometimes free so I recommend to check the website or by the door (they have the monthly program there).