MOON 850P Preamplifier The MOON 850P is a reference-grade, dual-mono analog preamplifier built to disappear in your system—delivering exceptional transparency, ultra-low noise, and uncolored musical detail. Its sophisticated two-chassis architecture separates the power supply/controller from the audio circuitry to preserve signal purity and maximize resolution. Inside, MOON’s M-Ray fully discrete R-2R volume control provides ultra-precise level matching across 530 steps, while i²DCf power regulation and extensive filtering keep the background pitch-black quiet. With fully balanced differential operation, flexible input configuration (including home theater bypass), and pro-level integration options, the 850P is engineered for demanding two-channel listening and high-end custom systems alike. The Moon 850P is part of ListenUp's MOON Preamplifier Collection. Check out ListenUp's REACH FOR THE MOON Trade-Up Program! What It's Good At: Preserving micro-detail and dynamics with a dual-chassis, dual-mono, fully balanced signal path Delivering whisper-quiet backgrounds and high resolution thanks to advanced power filtering and regulation Giving precise, repeatable volume and balance control with M-Ray R-2R circuitry and 530 fine steps Integrating seamlessly into complex systems with RS-232, SimLink, IR input, and dual 12V triggers Supporting serious source collections with multiple balanced/unbalanced inputs plus a monitor/tape loop Enabling “home theater ready” setups via configurable per-input bypass that skips the volume control MOON 850P Full Specifications: Type / Topology: Reference dual-mono preamplifier; fully balanced differential configuration Chassis Design: Two-chassis system (controller/power supply + separate audio-only preamplifier chassis) Balanced Inputs (XLR): 3 pairs (B1, B2, B3) Single-Ended Inputs (RCA): 4 pairs of line inputs (S1–S4) Monitor / Tape Loop (RCA): 1 pair (single-ended monitor loop in/out) Input Sensitivity: 200mV – 4.0V RMS Input Impedance: 11,000Ω Gain: 9dB Gain Offset (per input): ±10dB Home Theater Bypass: Per-input configurable bypass (volume control defeated) Balanced Outputs (XLR): 2 pairs (variable) Single-Ended Outputs (RCA): 2 pairs (1 fixed + 1 variable) Output Impedance: 50Ω Volume / Gain Control: M-Ray (fully discrete R-2R circuit) Volume Resolution: 530 steps in 1dB and 0.1dB increments Max Volume Lock: M-Lock user-selectable maximum volume per input Signal-to-Noise Ratio: 130dB @ full output (comparison chart lists >130dB @ full output) Frequency Response: 5Hz – 100kHz (+0/-0.1dB) Crosstalk @ 1kHz: 130dB (also commonly listed as ~-130dB @ 1kHz) THD (20Hz–20kHz): 0.0005% (comparison chart: THD @ 1kHz, 0dBFS < 0.0005%) Intermodulation Distortion: 0.0001% Power Supply Regulation: i²DCf (Independent Inductive DC Filtering), 1 inductor per IC in the audio signal path (40 stages total) Power Supply Design: Oversized dual-mono supply with 6 stages of DC voltage regulation and choke filtering Transformer: Custom proprietary toroidal transformer design (reduced magnetic/electrical/thermal loss) Microphonic Control: M-Octave damping system with main audio circuit board mounted on an 8-point floating suspension PCB: Four-layer PCB tracings for improved ground/power layout and shorter signal path Chassis Construction: Ultra-rigid design to minimize external vibration effects Remote Control: FRM-3 all-aluminum, full-function, backlit (Philips RC-5 protocol) Display: 8-character dot-matrix LED display Control / Integration: SimLink™ in/out (1/8" mini-jacks); RS-232 bi-directional control/status (DB9); IR input (1/8" mini-jack); 2x 12V trigger outputs (1/8" mini-jacks) Power Consumption (Idle): 25W AC Power Requirements: 120V / 60Hz or 240V / 50Hz Fuse (per voltage): 120V: 0.4A slow-blow (5 x 20mm); 230V: 0.2A slow-blow (5 x 20mm) Balanced XLR Pin Assignment: Pin 1 Ground / Pin 2 Positive / Pin 3 Negative Dimensions (each chassis): 18.75 x 4.0 x 16.5 in (W x H x D) / 47.6 x 10.0 x 41.9 cm Comparison Chart Dimensions (W x H x D): 18.8 x 4.0 x 16.5 in and 18.8 x 4.0 x 17.0 in Shipping Weight: 151 lb / 67 kg In the Box: AC power cable; FRM-3 remote control with three AAA batteries; three color-coded chassis interconnect cables; SimLink™ cable (1/8" mini plugs); owner’s manual; warranty & registration info (USA/Canada only) MOON 850P Q&A: Is the MOON 850P a fully balanced preamplifier? Yes. The 850P uses a fully balanced differential, dual-mono configuration designed to preserve signal integrity and reduce noise pickup—especially when using XLR connections. What’s the benefit of the 850P’s two-chassis design? The power supply/controller circuitry is housed in a separate chassis from the audio circuitry, helping isolate sensitive analog stages from electrical noise for improved accuracy and transparency. How many inputs and outputs does it have? It provides 3 pairs of balanced XLR inputs and 4 pairs of RCA line inputs, plus a dedicated RCA monitor/tape loop. Outputs include 2 pairs of balanced XLR (variable) and 2 pairs of RCA (one fixed, one variable). Can I set up a home theater bypass input? Yes. Each line input can be configured to be “home theater ready,” bypassing the 850P’s volume control so your AVR/processor can control level for that input. How precise is the volume control? Extremely precise—MOON’s M-Ray R-2R volume control offers 530 steps with 1dB and 0.1dB increments, plus per-input maximum volume lockout (M-Lock). Does it support custom installation and automation? Yes. It includes bi-directional RS-232 control/status, SimLink™ in/out for MOON component communication, an IR input for external receivers, and two 12V trigger outputs. Does it include a tape/monitor loop for recording or external processors? Yes. The 850P includes a single-ended (RCA) monitor/tape loop with dedicated input and output connectors for each channel. What accessories come in the box? You’ll receive an AC power cable, FRM-3 remote with AAA batteries, three color-coded chassis interconnect cables, a SimLink cable, the owner’s manual, and warranty/registration information (USA/Canada only). MOON 850P Downloads: MOON 850P User ManualMOON Preamplifier Comparison Chart
