Yo,
I have the same pedal, been using it with my Tiny Terror. This pedal is a true tube preamp just like the 1 in ur existing amp, but of course it is designed to allow u to overdirve the preamp tube in the pedal alot and create serious distortion. In fact, I think Blackstar now make an amp which essentially uses ths pedal for the preamp seciton, and of course adds poweramp and speaker.
So, there are at least 2 strategies for using it (well actually, infinite:) ):
1) Put ur amp on a clean setting, turn up the gain of the pedal to add distortion, but adjust the output of the pedal to be quite low i.e. the power of the signal coming out o the pedal is low. Now, ur amp is really just amplifying the dirty signal coming form the pedal as faithfuly as it can without adding any of its own dirt. If you turn up the amp it will start to distort the poweramp tubes of ur amp which will add another flavour of distortion. Since the output of the pedal is low, u are not pushing the amp's preamp tubes into distortion and you are basically hearing the pure preamp distorion of the pedal.
2) Same as above, but turn up the master volume (level, or whatever) of the pedal so that it is pushing ur amp's preamp tubes into overdrive as well, or even turn up the gain on ur amp as well. If you do this with the gain on the pedal set pretty low u will be just boosting the input signal to ur amp like an overdrive pedal and overdrivng the amps preamp tubes without adding any dirt from the pedal. If you do this with the pedal gain set high u will get both. Personally, I think the latter is not that useable and produces over the top results, but u need to experiment.
Of course, if u play around with the settings on both amp and pedal u have a pretty much infinite bunch of combinations and thus tones to play with (not all of them good), but this might give u something to start with. Also, u can then turn the pedal on and off giving u a kinda 2 channel setup, clean and dirty, this is good if u have a singal channel amp like the TT.