I’ve run a Schiit Freya+ through a Rogue Stereo 100, and I had no complaints about the sound quality. I did have a problem with the user interface: no balance control, no mono button, source selection can only move to the right (meaning you have to cycle through all five to get to the one to the left). But I did like the balanced connections, I also liked being able to run the Schiit in three different modes.
I too was looking at the RP-9, but happened on a McIntosh C100 for the same money. The RP-7 also has balanced connections.
I’m still not sure if I want the maintenance involved in a tube preamp, I did encounter instances of distortion with the Freya+ in tube mode. I think if you’re going to get the most out of a tube setup, you need to be willing to roll a few tubes.
Just my thoughts, experience.