Does non-variable output to an external preamp bypass the preamp in the rose?

I’m curious, if I use the rs150b strictly as a streaming DAC and run it to a preamp using a fixed output, does that process bypass the preamp section of the rs150b? Or is it merely taking the variable volume control and making it a fixed output?
Why? Well I’m wondering if the unit is adding a gain stage before my preamp or is it an unprocessed signal? I’m thinking it’s the latter because when I’ve tried the RS150b “as a preamp” I have to say I was unhappy with the sound (plus the loud “pop!” Sound it sent to my speakers when the rose unit was put into standby mode). BUT when I run the rose into my preamp it sounds completely different and better!