Fosi Audio ZP3 Balanced Preamplifier

Overview

The Fosi Audio ZP3 is a feature-rich, balanced line-level preamplifier designed to serve as a central control hub in modern hi-fi systems. It accommodates both balanced (XLR / TRS combo) and single-ended (RCA) connections, supports tone shaping (bass/treble) with a bypass option, includes a high-pass filter (HPF) for subwoofer integration, offers input memory, and supports 12V trigger in/out for system automation. The ZP3 is housed in a compact aluminum chassis and uses high-quality internal components to deliver clean, low-noise performance.

Key Features & Highlights

• Input & Output Configuration
  • Inputs: 2 × RCA (single-ended) + 1 × balanced input (XLR / TRS combo)
  • Outputs: RCA (single-ended), XLR balanced, and a Subwoofer (SUB-out) output
• Tone Controls and Bypass
  • Bass control range: ±12 dB
  • Treble control range: ±6 dB
  • “Bypass” switch to skip the bass/treble circuits for a purer signal path
• High-Pass Filter (HPF) / Crossover Options
  A built-in HPF toggle switch provides three cutoff settings:
  1. 20 Hz – 20 kHz (full range)
  2. 80 Hz – 20 kHz
  3. 120 Hz – 20 kHz
     This allows filtering of low frequencies going to the main outputs so a subwoofer can manage the bass.

• Balance Control & Input Memory
  • A balance knob adjusts left-right channel levels
  • The unit “remembers” the last volume level per input, so switching between sources restores the prior volume
• 12V Trigger In / Out
  Allows synchronized powering on/off with other gear (e.g. DACs, amplifiers) supporting 12V trigger signals
• Remote Control
  Includes an IR remote to adjust volume, input selection, and power functions. Some remote functions overlap with other Fosi devices.
• Op-Amp Rolling / Replacement Supported
  The design supports socketed op-amps, letting advanced users experiment with different op-amp models to tailor sound character
• Compact & Shielded Construction
  The chassis is made of aluminum alloy, offering a combination of durability, compact footprint, and electromagnetic shielding

Verified Technical Specifications

What’s Included in the Package

• Fosi Audio ZP3 Balanced Preamplifier
• IR Remote Control
• 12V Trigger Cable
• Power Cable

Usage Tips & Best Practices

• Power Sequencing:
  Turn on the ZP3 before powering your amplifier; when powering down, reverse the sequence to avoid pops or clicks.
• Volume Caution:
  The digital-style rotary volume has no visual indicator. Always start from a low volume when powering on to avoid inadvertent spikes.
• Bypass vs Tone Use:
  Use “Bypass” when you want the cleanest signal (no tone shaping). If tone control is engaged, you may see slight deviations in response.
• HPF & Subwoofer Setup:
  Use the HPF switch to attenuate low frequencies on the main outputs (80 Hz or 120 Hz) when working with a subwoofer, so the sub handles the deep bass.
• Op-Amp Replacement:
  If rolling op-amps, make sure the correct orientation (pin1 / notch) is aligned to avoid damage.
• Memory Behavior:
  Each input retains its last volume setting, so when switching inputs, you return to that stored level—handy, but watch for volume jumps if the stored level is high.