DON’T feed the A90 into the Rogue. Take the preamp output from the Rogue (one of the 2 RCA outputs on back, NOT the fixed level one) and feed that into the A90. Then plug your headphones into the A90 (or Schiit). Find a reasonable level on the A90 or Schiit (probably somewhere around unity gain to +6dB or so) and leave it there, using the Rogue for remote volume control. That should be far superior to the other way around.
Rogue has a long and annoying history of including pathetic headphone jacks as “bonus” features in otherwise very nice preamps and integrated amps. I wish they would stop doing this. Do it right, or leave it out. Ironically, by all accounts their dedicated RH-5 headphone amp is a good unit. But their “bonus” headphone jacks suck - don’t even bother plugging your headphones in.
By using the RP-1 as a normal preamp output into a decent headphone amp (of your choice) you won’t be crippling your headphone’s performance, and you’ll benefit from the remote-controlled volume (which most headphone amps lack).