From Line6 Product Manager....
Hybrid cabs start out as oversampled 2048-point IRs, but are optimized to utilize way less DSP without losing definition. You can pick one of 16 mic models (or in the case of dual cabs, two of 16 mic models), change the mic distance from 1" to 12" in half-inch increments, apply early reflections, and filter them with low and high-cut filters. That's pretty much it.