Released in the '80s, the PDS 2000 might be called the harbinger of the Line 6 DL4. It features three modes—delay, sampler and trigger—which are the three things the DL-4 does. The sampler function is a two-second looper accessible via the left footswitch. In trigger mode, a footswitch is connected to the trigger input, and the footswitch plays a stored loop just once, but you can use a click track or drum machine instead of a footswitch to trigger the stored sample as well.