Apollo twin x quad The Universal Audio Apollo Twin X QUAD is a premium 10-in / 6-out desktop Thunderbolt 3 audio interface designed for professional tracking, monitoring, and mixing. It is highly regarded for its elite-class analog-to-digital (A/D) and digital-to-analog (D/A) audio conversion. The standout feature of the "QUAD" variant is its four onboard SHARC DSP processors, which handle heavy UAD plugin processing directly inside the hardware. This allows you to track and monitor through legendary analog emulations in real time with near-zero latency, completely bypassing your computer's CPU resources.