Audio Research D-400

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The Audio Research D-400 is a high-performance tube preamplifier designed and built by the renowned American audio company, Audio Research Corporation. It is a successor to the highly acclaimed D-300 model, and is considered one of the finest tube preamps currently available on the market.The D-400 features a fully balanced signal path, with dual mono sections and a total of seven input options (four single-ended and three balanced). The preamp employs hand-selected, matched, and tested tubes throughout, including four 6H30's in the input stages, two 6922's in the driver stages, and a single dual-triode 6550EW in the output stage.One of the unique features of the D-400 is its external power supply, which is sold separately and can also be used to power an Audio Research CD player, phono stage, or other compatible Audio Research components. The external power supply is said to improve overall sonic performance, reduce low-level noise, and increase power supply stability.The D-400's sound signature is described as rich, lush, and detailed, with a full-bodied, lifelike presentation that is particularly well-suited to the reproduction of live acoustic music, voice, and classical recordings. It is also known for its low noise floor, wide dynamic range, and excellent control of micro-dynamics and fine detail.Overall, the Audio Research D-400 is a high-end tube preamplifier that is widely regarded as a benchmark reference component in its category, and represents a significant investment in the pursuit of natural, musical tone and detail.

Power Output: 200W into 8Ω (stereo)
Frequency Response: 4Hz to 100kHz
Distortion:
Damping Factor: 150
Speaker Impedance: 4Ω (minimum)
Input Sensitivity: 1.91V
Signal to Noise Ratio: 106dB
Dimensions: 480 x 228 x 450 mm
Weight: 33.2 kg
Year: 1991
Price: USD $4,995 (1992)