People seem to like this unit a lot & I've run across used ones. I've noticed folks seem to be looking for sound cards. Are they discontinued and a problem to find? Will th unit work without them? Can patterns, fills, songs be programed into the unit? I've only used a Dr. Rythme and a Yamaha rythme machine so I'm very inexperienced but looking for some thing with top quality sounds and programability at a cost I can afford- Thanks