Hi there,
During my last trip I wanted to make sure to visit this coffeeshop : " Mr K & Co ", they carry somme good genetics. It's not far from " 1st Hulp " another really good shop. However the prices kind of piss me off a bit, but when you want variety/novelty and can't grow anymore... It's still possible to find good deals through the city mostly around the center. The stud, Club media, ... i've heard about the kade also, just a few example.
Try a visit to Boerejongens west (the one in the center I never liked cause the budtender are "speedy").
On a side note : I'm heading to Barcelona next for a little time. I much prefer the CSC way of doing things than in Coffeeshops : you are a member of their association and they consider you as such and not as a customer. You aren't force to buy any drinks or anything at all..but just enjoy the club facility and their products
If anyone needs help in getting to the clubs you can PM me it will be a pleasure for me to help you find what you want as yu can't just ring to their door and become a member, you need to get a recommendation/invitation of some sort.
One of the club I visited during my previous trip has the Sublimator, for example... Generally they all have good herbs, resins and concentrates but it's better to know where you go before to pay a membership. Cheaper than in NL and more variety/quality. I don't say there isn't in Dam, just a general consensus.