What you are looking for is "prive" houses.
They are well run private brothels no rush no gangsters and totally legal.
If you google it you will find loads of them and you can email them and get more info.
They are not more expensive than the standard "suck and fuck" of the RLD as you get an hour for about €80- €100 and also more services on offer too often anal etc and jacuzzis etc etc the value in Amsterdam would put the girls here to shame (sad but true)
IMPORTANT !
If you are going to one find the name of a street nearby and ask the taxi to bring you there if you tell the taxi driver what you are up to he will accompany you to the door and
then wait for his commission this then goes on your bill !
http://www.amsterdamlogue.com/amsterdam-brothels.html