Auronthas - You're correct that the DAC Pre adds analog inputs; that's the only difference. I am running DAC 1 in balanced mode into the 400xi. My understanding is that balanced is the preferred choice but I can't give you the technical explanation other than the gain is slighly higher.
I would not say that introduction of the DAC 1 warmed up the system. This DAC is noted for being very detailed and accurate which is what I was seeking. If you are looking for a warmer sound you may want to consider some of the tube dacs (wavelength brick is in the same price range). There seem to be a lot of new USB dacs coming to the market such as Musical Fidelity and Cambridge.
If you make the move to a DAC, you may find yourself never handling a CD again other than to put in your car (unless you have a car with an ipod jack). It is extremely convenient.
I would not say that introduction of the DAC 1 warmed up the system. This DAC is noted for being very detailed and accurate which is what I was seeking. If you are looking for a warmer sound you may want to consider some of the tube dacs (wavelength brick is in the same price range). There seem to be a lot of new USB dacs coming to the market such as Musical Fidelity and Cambridge.
If you make the move to a DAC, you may find yourself never handling a CD again other than to put in your car (unless you have a car with an ipod jack). It is extremely convenient.