Yeah I don't see this working out too well with just an interface. You'll have a much easier time with software. I love the T-Racks clipper. You just have to be real careful with clipping. If you're clipping the whole mix, you have to be aware of what's peaking and where. All it should really be doing is shaving a dB or two off the peaks of the drums. Anything else clipped just sounds like, well, clipping distortion, which is terrible. Maybe you're driving it too much?
FWIW the few times I've tried clipping our apogees at the studio I've sent the mix out the patch bay, into a Manley vari-mu or Smart C2, and raised the output gain of the compressor so I'm just clipping the last dB or two of snare peaks coming back in. Like egan said, you need something to raise the gain a little.