The D4 was an affordable and fully professional Drum and Percussion sound module. It featured 500 drums sounds, sampled at 48kHz and stored on an internal ROM chip. The sounds cover the whole gamut, from great acoustic drum types to electronic drum sounds. Orchestral and ethnic percussion sounds and various percussive effects are also available. There are 21 programmable drum kits as well. And the D4 has full 16-channel MIDI implementation. The D4 has 12 trigger inputs allowing drummers to trigger its sounds from acoustic or MIDI pads. Engineers and musicians can also trigger drum sounds from the D4 using the trigger inputs and any external sound sources from tape or other studio gear. A hi-hat pedal jack allows use of a footswitch to create more realistic hi-hat effects. There are also 4 independent outputs for either 4 mono outs or 2 stereo outs. The D4's only limitation, is editing. Drum sounds can only have their tuning, panning and respective volumes edited. However, drums can be assigned to special groups so that special drum characteristics can be created such as closed hihats cutting off open hihat sounds, etc.