I found the most amazing bamboo hardwood floors that I wanted for my studio. However, I believe that in order to install hardwood flooring over concrete - you would need to install a layer of 3/4" plywood since hardwood floor gets nailed in. The plywood gets nailed into the concrete. Its not a floating floor like laminate. I was dealing with low ceilings so I decided to go with laminate to save to 3/4" height and also the actual laminate flooring is much thinner than the hardwood. I'm sure others can offer better advice than me but it would seem that any underlayment meant to increase acoustic isolation would be sort of "snake oil" as you put it. The floor is usually firmly coupled to the concrete. There are probably some companies that do offer floating hardwood floors but it's not that common.quick question: looks to me (according to F. Alton's book, for example) that some sort of FELT underlayment is about as good as it gets, when putting hardwood floors down on a concrete slab.
Additionally, I'm in a basement and none of the hardwood mfg. had warranty that cover basement installation.