The Fosi Audio BOX X5 MM/MC Phono Preamplifier delivers detailed vinyl playback with precision RIAA equalization, premium OPA1612 circuitry, and compatibility with moving magnet and moving coil cartridges. Featuring four adjustable gain settings of 38dB, 48dB, 56dB, and 66dB, selectable cartridge loading, gold-plated stereo RCA connections, and a dedicated ground terminal, the BOX X5 makes it easy to integrate a turntable into a high-fidelity audio system. With its low-noise design, durable aluminum alloy chassis, and included 16V AC power supply, this compact phono stage offers excellent flexibility for vinyl enthusiasts and cartridge upgrades.
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Fosi Audio BOX X5 MM/MC Phono Preamplifier with 4-Level Gain Adjustment

Bring greater clarity, detail, and musical depth to your vinyl collection with the Fosi Audio BOX X5 MM/MC Phono Preamplifier. Designed for turntable enthusiasts looking to upgrade their analog audio system, the BOX X5 combines precision RIAA equalization, four selectable gain settings, and compatibility with both moving magnet (MM) and moving coil (MC) cartridges in a compact, all-aluminum enclosure. Featuring premium audio components, low-noise circuitry, and gold-plated RCA connections, the BOX X5 provides the essential signal amplification and equalization needed to enjoy vinyl records through compatible stereo amplifiers and powered speakers.

At the heart of the BOX X5 is a carefully engineered phono amplification circuit designed to preserve the subtle details captured in your favorite records. Its Texas Instruments OPA1612 operational amplifier works alongside 2% precision polyester film capacitors, 0.1% high-precision film resistors, and specialized copper-lead audio capacitors to minimize unwanted noise and signal distortion. Precise RIAA equalization restores the tonal balance of vinyl recordings, helping deliver accurate bass, natural midrange reproduction, and clear high-frequency detail. With a manufacturer-rated signal-to-noise ratio of at least 92dB and total harmonic distortion of 0.009% or less under specified test conditions, the BOX X5 provides a clean and reliable foundation for dedicated analog listening.

One of the BOX X5's most versatile features is its adjustable gain system, which provides four selectable amplification levels of 38dB, 48dB, 56dB, and 66dB. This allows the phono stage to accommodate a wide range of cartridges with different output levels, from higher-output moving magnet models to lower-output moving coil designs. A dedicated MM/MC impedance switch provides the appropriate input loading options, with 47kΩ for MM cartridges and 100Ω for MC cartridges. These controls make it easy to tailor the phono stage to compatible cartridges without replacing your entire turntable or audio system.

Connecting the Fosi Audio BOX X5 to your Hi-Fi system is straightforward. A stereo RCA input accepts the low-level phono signal from your turntable, while a separate stereo RCA output sends the equalized and amplified signal to a compatible line-level input on an integrated amplifier, preamplifier, or powered speaker system. A dedicated grounding terminal provides a convenient connection for the turntable's ground wire, helping minimize unwanted hum and interference. Its compact design also pairs naturally with other Fosi Audio components, including the V3 and ZA3 amplifiers, making it an excellent addition to a space-conscious vinyl listening setup.

The BOX X5 is built around a durable aluminum alloy chassis that helps shield its sensitive phono circuitry from electromagnetic interference. Its minimalist design features a convenient front-panel power button and indicator light, while the rear panel provides access to the RCA connections, adjustable gain selector, cartridge impedance switch, and grounding terminal. Powered by an included 16V AC adapter, the BOX X5 offers straightforward installation without complicated setup menus or additional digital components. Whether you're adding phono capability to an amplifier without a dedicated turntable input or upgrading from a basic built-in phono stage, the Fosi Audio BOX X5 delivers versatile cartridge support, precision analog circuitry, and high-fidelity performance in one compact component.

Specifications

• Brand: Fosi Audio
• Model: BOX X5
• Product Type: MM/MC phono preamplifier
• Audio Channels: 2-channel stereo
• Supported Cartridge Types: Moving Magnet (MM) and Moving Coil (MC)
• Phono Equalization: RIAA equalization
• Amplification Circuit: Low-noise analog phono preamplifier
• Operational Amplifier: Texas Instruments OPA1612
• Capacitors: 2% precision polyester film capacitors and copper-lead audio capacitors
• Resistors: 0.1% high-precision film resistors
• RCA Connections: Gold-plated RCA jacks
• Available Gain Settings: 38dB, 48dB, 56dB, and 66dB
• 38dB Gain: Recommended for phono signals above 2mV
• 48dB Gain: Recommended for phono signals around 2mV or lower
• 56dB Gain: Recommended for low-output phono signals around 0.5mV or lower
• 66dB Gain: Recommended for very low-output phono signals around 0.25mV or lower
• Gain Adjustment: Four-position rear-panel rotary selector
• Cartridge Loading Selection: Dedicated MM/MC impedance switch
• MM Input Impedance: 47kΩ
• MC Input Impedance: 100Ω
• Input Loading Options: 47kΩ or 100Ω
• Total Audio Input Types: 1
• Analog Phono Input: 1 × stereo RCA pair
• Input Signal: Low-level MM/MC phono signal from a compatible turntable
• Total Audio Output Types: 1
• Analog Audio Output: 1 × stereo RCA pair
• Output Signal: RIAA-equalized, amplified analog audio for a compatible line-level input
• Output Impedance: 10kΩ, as listed in the manufacturer user manual
• Ground Connection: 1 × turntable grounding terminal
• Signal-to-Noise Ratio: At least 92dB (38dB gain, 5mV input)
• Total Harmonic Distortion: 0.009% (38dB gain, 5mV input)
• Noise Floor: 37µV (38dB gain, 5mV input)
• Frequency Response: 20Hz–20kHz (±0.015dB)
• Power Button: Front-panel push-button control
• Power-On Operation: Press and hold approximately 2 seconds
• Power-Off Operation: Single press
• Power Indicator: Front-panel LED
• Volume Control: No dedicated listening-volume control
• Chassis Material: Aluminum alloy
• Chassis Design: Compact metal enclosure with electromagnetic interference shielding
• Finish: Black
• Dimensions: 4.1 × 6.5 × 1.4 inches (manufacturer-listed)
• Power Input: AC 15–18V
• Included Power Supply: 16V/1A AC adapter
• Power Supply Type: External AC-output adapter; not a DC adapter
• Built-In DAC: No
• Digital Audio Inputs: No
• Bluetooth: No
• Wi-Fi: No
• Apple AirPlay: No
• Built-In Music Streaming: No
• USB Audio: No
• HDMI Inputs: 0
• HDMI Outputs: 0
• Headphone Output: No
• Speaker-Level Outputs: No
• Direct Passive Speaker Amplification: No
• Stereo Speaker Pairs Powered: 0
• 12V Trigger Input: No
• 12V Trigger Output: No
• App Control: No
• Remote Control: No
• Manufacturer Warranty: 24-month limited warranty
• Included Accessories: Fosi Audio BOX X5 Phono Preamplifier, 16V AC power adapter, and user manual

What It's Great At

• Versatile MM and MC Cartridge Compatibility: Supports both moving magnet and moving coil cartridges, making it easy to integrate the BOX X5 with a wide range of compatible turntables and cartridge upgrades.
• Four Adjustable Gain Settings: Select 38dB, 48dB, 56dB, or 66dB of amplification to better match the output voltage of your turntable cartridge.
• Accurate RIAA Phono Equalization: Dedicated RIAA equalization circuitry restores the intended tonal balance of vinyl recordings for accurate, engaging analog playback.
• Premium Low-Noise Audio Components: An OPA1612 operational amplifier, precision film resistors and capacitors, and gold-plated RCA terminals help minimize unwanted noise and preserve musical detail.
• Simple Stereo System Integration: Dedicated RCA input and output connections, a turntable ground terminal, and rear-panel cartridge loading controls make installation straightforward.
• Durable All-Aluminum Construction: A compact aluminum alloy enclosure helps shield the sensitive phono circuitry from electromagnetic interference while complementing modern and traditional Hi-Fi systems.

FAQ Section

Q: What is the Fosi Audio BOX X5 used for?
A: The Fosi Audio BOX X5 is a dedicated phono preamplifier designed to amplify the low-level audio signal from a turntable cartridge and apply RIAA equalization. This creates a signal suitable for connection to a compatible line-level input on an integrated amplifier, preamplifier, or powered speaker system. It is especially useful for turntables and amplifiers that do not include a compatible built-in phono stage.

Q: Does the Fosi Audio BOX X5 support moving magnet and moving coil cartridges?
A: Yes. The BOX X5 supports both moving magnet (MM) and moving coil (MC) cartridges. It includes selectable input loading of 47kΩ for MM cartridges and 100Ω for compatible MC cartridges, along with four gain levels to accommodate different cartridge output voltages. Always verify the loading requirements of your specific cartridge.

Q: What are the four gain settings on the Fosi Audio BOX X5?
A: The BOX X5 features selectable gain settings of 38dB, 48dB, 56dB, and 66dB. Lower settings are typically used with higher-output cartridges, while higher settings accommodate lower-output designs. Fosi Audio recommends 38dB or 48dB with the 47kΩ MM loading setting and 56dB or 66dB with the 100Ω MC loading setting as starting points.

Q: What is RIAA equalization, and why does the BOX X5 need it?
A: RIAA equalization is the standardized frequency correction used in vinyl playback. During record production, bass frequencies are reduced and high frequencies are increased to help optimize the recording process. The BOX X5 applies the complementary playback equalization curve to restore the intended tonal balance of the music while amplifying the cartridge's low-level signal.

Q: How many audio inputs and outputs does the Fosi Audio BOX X5 have?
A: The BOX X5 has one stereo RCA phono input and one stereo RCA analog output. It also includes a separate grounding terminal for connecting the turntable's ground wire. It does not have digital audio inputs, headphone outputs, speaker binding posts, or balanced XLR connections.

Q: Can I connect the Fosi Audio BOX X5 directly to powered speakers?
A: Yes. The BOX X5 can connect to compatible powered speakers with analog line-level inputs and their own volume control. It can also connect to an integrated amplifier or separate preamplifier. The BOX X5 cannot directly power passive speakers, and its output should connect to a line-level input rather than another phono input.

Q: Does the Fosi Audio BOX X5 support Bluetooth, Wi-Fi, or streaming music?
A: No. The BOX X5 is a dedicated analog phono preamplifier and does not include Bluetooth, Wi-Fi, Apple AirPlay, or built-in music streaming services. It is specifically designed for playback from compatible turntables rather than digital audio sources.

Q: What power supply does the Fosi Audio BOX X5 use?
A: The BOX X5 uses an external 16V AC power adapter, which is included. Its supported input range is 15–18V AC. The unit requires an appropriate AC-output adapter and should not be powered using a conventional DC power supply.