I have 50 yr old red oak parquet floors mixture of heartwood and sapwood that were finished with polyurethane (no stain). I stripped them, then sanded with 80, 100 and 150 grit (random orbital sander). When wet color is amber/orange. I want to stain with a light red maybe add a hint of brown to downplay this amber/orange. I want to deaccentuate the grain - floor is busy enough don't need to highlight it. Products will be Bonakemi DriFast stain with Traffic or Duraseal stain with Bonakemi Traffic. I think to downplay the grain I should use wood conditioner first. Do you agree? Any suggestion are welcome.

A conditioner is in reality, a neutral oil stain. A stain base without the pigment. So, if you use that, to get the color you're looking for, you'll need to go darker as the conditioner will "seal" the wood somewhat. The open grain nature of oak is what it is. To get a more monochromatic appearence, try a semi-transparent stain. This has a heaver pigment that "paints" the wood. As always, test, test, test on samples first.

If you don't want the ambered look, try a a sample of the straight waterbase look. A waterbase sealer will dry lighter than the products you've mentioned. Much less stain definition. As time goes on it will apear more 'washed-out'. Any stain, from neutral on up will just accent the grain.