Coaxial coils have been introduced recently, the way of interfacing these coils impacts the achievable SNR. In this work, the interfacing circuitry is studied to optimize sensitivity and ensure safety. Performance tests on the bench and in the MR scanner were done for 8-cm 123 MHz coaxial coils, operated at their self-resonance. It was found that a high inductance across the port and symmetric matching capacitors increase SNR. A balun and a phase shifter for preamp decoupling are described, the correct positioning of a fuse is demonstrated. Miniature preamplifiers and toroid inductors minimize size and weight to obtain maximum flexibility.