Electrical metrology has historically relied on precise current comparators, which play a central role in determining accurate current ratios. Conventional devices, however, depend on inductive pickup coils or cryogenic infrastructures such as SQUIDs, imposing limitations on bandwidth, complexity, and operational environments. To address these challenges, we propose a unified comparator architecture based on nitrogen-vacancy (NV) centers in diamond. The system replaces conventional magnetic pickup or flux feedback mechanisms with a solid-state quantum magnetometer that optically detects magnetic flux in the air-gap of a magnetic core. The NV sensor provides sensitivity to both AC and DC magnetic fields, enabling seamless operation across different metrological regimes, and fully compatible with a modern power electronics requirement. The proposed architecture offers key advantages such as complete electrical isolation, compact system, and potential scalability for portable or embedded applications. Modeling and recent advances in NV magnetometry suggest that the required sensitivity is achievable with current technologies. By addressing both AC and DC current measurement requirements in the field of power industries and fundamental electrical standards, this concept paves the way toward a next-generation current ratio standard.