With modern techniques, the MPX-4Aii's transformerless input design rivals and even surpasses the best transformer-input designs that were the standard in the industry earlier. This is especially true in low-level input applications to achieve extremely low noise floor, minimum distortion, wide bandwidth and linear phase response. This approach can be obtained a warm sound, crystal clear and fast response, getting a step closer to the human ear characteristics.
Each MPX-4Aii unit uses a Class A, auto-bias bridge configuration, hybrid input stage preamplifier based on hand-selected transistors for the lowest of noise, and the lowest possible base-spreading resistance and collaterally matched for perfect balance, and biased at the precise levels that make them maximally insensitive to thermal drift. As a result, no offset crowding occurs, and the dynamic range remains wide open. Because of the wide gain-bandwidth parameters of these specially-selected transistors, and the super-low impedance characteristics, and the vanishing circuit reactance, the impulse response is optimum, and phase-delay distortion undetectable. Gain adjustments are made with balanced differential-mode cancellation, preserving the excellent DC offset characteristics, without altering the loop feedback characteristics from their optimal configuration.
