The high pass filter really is the most obvious component missing from the Prophet '08 design. If you wanted that distinctive HP gradual removal of lower frequencies until the sound disappears into thin air, then the P'08 can't help you. But if you wanted merely to eliminate some of the lowest frequencies, say, to reduce boominess, you could always use the 2-pole filter, some resonance, a very narrow pulse width (as you mentioned), and even a graphic equalizer. But these would be no substitute for sweeping a patch with the real thing.