Audio Research SP-11 Tube Preamplifier with SP-11PS Power Supply Reference High End Audio Component Offered is an Audio Research SP-11 reference tube preamplifier complete with its matching SP-11PS external power supply. Introduced during the golden era of high-end American audio, the SP-11 is regarded as one of Audio Research's most significant preamplifier designs. Combining exceptional phono-stage performance with advanced line-level circuitry, it became a benchmark component among audiophiles and professional listeners. The unit employs six 6DJ8/ECC88 vacuum tubes. It features extensive input/output flexibility, selectable phono impedance settings, phase inversion, tape-monitor functions, and a dedicated external power supply for improved performance and noise reduction. Specifications: * Brand: Audio Research * Model: SP-11 * Power supply: SP-11PS * Type: Tube preamplifier * Country of origin: United States * Era: 1980s * Channels: Stereo (2-channel) * Tube complement: 6 × 6DJ8 / ECC88 * Color: Silver Dimensions (each chassis): * Width: 48 cm * Height: 13.4 cm * Depth: 26 cm Weight: * SP-11: 6.4 kg * SP-11PS: 6.8 kg * Total: 13.2 kg Condition: Reported to be in perfect working condition. Please review all photographs carefully to confirm the exact cosmetic condition and completeness. A highly respected vintage Audio Research reference preamplifier, sought after by collectors and audiophiles for its musical performance and historical importance in high-end audio.