With kick, snare and two overheads, the QUAD incorporates the best of two microphone placement techniques: close miking and overhead (ambient) miking.
The D6 for kick drum and the i5 for snare are considered the two microphones every drummer must have. The kick and snare are considered the core of any drum kit and the foundation for every groove. Close miking ensures that they will be captured in the mix. If either the kick or the snare is unable to be heard, there is simply no groove. Being high SPL dynamic microphones, the D6 and i5 excel at close miking. This miking technique is required in order to capture the attack and percussive sound of the drum. Also, by having the mic close to the source of the sound, it helps to isolate the sound of each drum and separate it from the rest of the kit.
Overhead (ambient) Miking
Supporting the idea that less is more, there are many engineers who will use just two overhead mics to capture the natural sound of the complete drum kit. With two overhead mics, positioned correctly, it is absolutely true that you can capture the transients, tonality and balance of the kit in a completely phase-coherent manner. The Audix DP QUAD 4-piece drum microphone pack is the simplest and most effective combination of microphones that will allow you to capture the depth and imaging of a full drum kit.