I am getting ready to have engineered hardwood floors installed onto a wooden subfloor. The hardwood floor will be nailed down.

I also have radiant heat installed, using heat transfer plates that have been screwed to the subfloor from below. The water temperature will be in the low 90s.

Hence, I am now looking for a recommendation for a proper underlayment for the engineered hardwood floor that has the following characteristics (in that order):
– no thicker than 1/8″
– very low or zero VOC and free of other questionable products
– low R-value
– sound absorbing

Any guidance and suggestions for a specific product?

Thank you,
Torsten