It shouldn't -- the headphone out on tthe D1 is separate from the op amp driven headphone out. The thing you'll have to find out is whether the D1's RCA outs are volume controlled or fixed output -- I'm pretty sure they're fixed and the headphone output is the only one that responds to the volume control, but I'm not 100% on that.
In the case that the RCAs are also controled by the volume control, then you'll just have to play around with finding a level on the D1 that gives you the best control range, and lowest noise on the Crack. Then just mark where that position is and set it there whenever you use the Crack.
-- Jim
Jim Rebman -- recovering audiophile
Equitech balanced power; uRendu, USB processor -> Musette DAC -> 5670 tube buffer -> Finale Audio F138 FFX -> Cain and Cain Abbys near-field).
s.e.x. 2.1 under construction. Want list: Stereomour II
All ICs homemade (speaker and power next)