Parallel imaging techniques have developed very rapidly, and realization of their full potential has required the design of magnetic resonance (MR) scanners with ever-increasing numbers of receiver channels (32 to 128). In particular, 1.5- and 3-Tesla fast MR imaging applications are now used in everyday clinical practice. Both strengths require maximum achievable signal-to-noise ratio (SNR) and multi-detector array coil optimization within the framework of the parallel imaging scheme for more advanced and faster clinical MR scanning. Preamplifiers are key components in the detector array coils and serve many functions beyond mere signal amplification. One critical function is to aid in the decoupling of individual coils, which is essential for optimal SNR and the performance of parallel imaging. To support a large number of detector array coils for parallel imaging, preamplifiers must be physically very small so that they may be tightly packed together to form an optimized detector array. The author herein reviews the state-of-the-art work reported by those skilled in the art to consider the rationale for determining how many channels are enough and how fast we can go. The paper explores the important and fundamental principles of RF array coils for MR imaging and reviews cutting-edge array coils, including those for transmit-SENSE or parallel transmission applications. The future of radiofrequency (RF) coil technology is also considered.