Jimmy, using an integrated amp behind a dedicated pre-amp is not the way to truly get an idea of how seperates will sound. Why? your nice clean signal from the pre-amp will suffer deterioration from exposing it to the workings of an integrated amp. Integrated amps, as great as they are, tend to affect seperation to a degree. In order for you to truly "audition" seperates, you need a single dual mono amplifier, dedicated only to processing the signal coming out of your dedicated 2 channel pre-amp.
Good luck!
Good luck!