Oxidoreductase involved in lignan biosynthesis. Catalyzes the NADPH-dependent reduction of phenylcoumaran benzylic ethers. Converts dehydrodiconiferyl alcohol (DDC) to isodihydrodehydrodiconiferyl alcohol (IDDDC), and dihydrodehydrodiconiferyl alcohol (DDDC) to tetrahydrodehydrodiconiferyl alcohol (TDDC). (-)-dehydrodiconiferyl alcohol + H(+) + NADPH = (S)-isodihydrodehydrodiconiferyl alcohol + NADP(+) (+)-dehydrodiconiferyl alcohol + H(+) + NADPH = (R)-isodihydrodehydrodiconiferyl alcohol + NADP(+) (2R,3S)-dihydrodehydrodiconiferyl alcohol + H(+) + NADPH = (S)-tetrahydrodehydrodiconiferyl alcohol + NADP(+) (2S,3R)-dihydrodehydrodiconiferyl alcohol + H(+) + NADPH = (R)-tetrahydrodehydrodiconiferyl alcohol + NADP(+) Expressed in flowers. Expressed at low levels in stems. Belongs to the NmrA-type oxidoreductase family. Isoflavone reductase subfamily.