You have a) a drum machine, b) no reverb, and c) a DDL. Try this for size: set your DDL to a short echo setting — somewhere in the region of 50mS (experiment for an exact setting). Turn the feedback/regeneration up a tad, and here that kit take life. Boom crash, it goeth, sounding to all the world (and your portastudio) like the drums are suddenly made large and real. That's because the short delay does a good impression of a small room's reverbative characteristics, doubling the sounds of each drum.