Neither of these pedals are attempting to break new ground, both opting for a traditional delay with familiar sound. The sonic qualities of the DL4, however, are hard to beat; Line 6’s Stompbox modeler produces unique delay functions that are warm and distinct. The DD-20 is not intended to be vastly different to any other pedal, just more effective.

The videos below should give you some idea of the sound and tone characteristics of each pedal.
 

Neither of these pedals are attempting to break new ground, both opting for a traditional delay with familiar sound. The sonic qualities of the DL4, however, are hard to beat; Line 6’s Stompbox modeler produces unique delay functions that are warm and distinct. The DD-20 is not intended to be vastly different to any other pedal, just more effective.

The videos below should give you some idea of the sound and tone characteristics of each pedal.