I haven't had the Rag 2 in my hands long enough to verify what I will say about the gain stages of the Rag 1 and assume of the two.
Gain 1 to me sounds like the Pass Aleph amp series or the Adcom GFP-750 pre-amp. Like there is no line stage engaged. Very pure and transparent, but sagging at the freq extremes. Very cool for mid centric music. No go for larger scale music.
Gain 2 has the LS turned on, but delivers admirable levels of clarity. However LS on does not explain all the extra gain, so there is some strapping or a different circuit path where it picks up some db. I listen to all my cans about 95% in this mode. Note: Rag 1 first 4 watts is Class A, then slides to AB. Rag 2 is Class A for 1 watt, then AB. That can be heard in this Gain. In the Rag 1 I think its all Class A. Can't say for the 2. You can drive the HE-6 or HE-6se here, even though the volume knob gets to 4 O'Clock at times on the 1, and the specs say the 2 has even a bit more kick than the 1 in this gain.
Gain 3 Much louder, must be a strapping. I find it potent, but lacking detail and finesse you find in the other two stages. Basically for speakers. I never use it on cans
This is my take, never could get any details from the Schiit boys, or reviews, so take it for what its worth.