Cafe Alto is indeed one of the places to check out its located on the 'Leidsedwarsestraat' right off the busiest square: Leidseplein (Leidsesquare). The square were places like Paradiso & Milkyway are also located. You might check with the bimhuis, http://www.bimhuis.nl/
. Might also wanna check out Utrecht (my home town), only 20 minute train ride from A'dam central station. http://www.sjujazz.nl
although the site is in dutch youll probably be able to find your way around it enough to contact them.
edit: oops missed vincent's post there.