Fosi Audio ZP3 Preamplifier

Complete Audio Control Hub with Audiophile-Grade Performance

The preamplifier market has evolved significantly in recent years, with more affordable options offering features and performance that were once the domain of high-end equipment. Fosi Audio has consistently delivered budget-friendly audio products that punch above their weight, and their ZP3 preamplifier continues this tradition with an impressive array of features and connectivity options that would satisfy even demanding audiophiles.

From using the ZP3 for a few weeks I found it to be a versatile preamplifier that serves as a nice audio control hub in a small system, offering multiple inputs, outputs, and a host of thoughtful features including a properly implemented high-pass filter, trigger inputs/outputs, and tone controls. But it does have one problem that can make it a little annoying to use.

But, before I get into the details, lets have a look at the unboxing:

Unboxing and Build Quality

The Fosi Audio ZP3 arrives in a sturdy, well-designed box that protects the unit during shipping.

Opening the box reveals the preamplifier securely nestled in protective foam, along with accessories and documentation.

Inside the box, you’ll find:

The complete package includes:

• Fosi Audio ZP3 Preamplifier
• Remote control
• Power adapter
• User manual
• Trigger cable
• RCA cables

The ZP3 features a solid aluminum chassis that feels substantial and well-built. The front panel has an elegant, clean design with a central volume knob and several smaller knobs for balance and tone controls.

The build quality is impressive for a component in this price range. The knobs turn smoothly with good resistance, giving a premium feel to the user experience. The chassis provides adequate ventilation while maintaining a sleek appearance that would look at home in any audio setup.

Features and Performance

The Fosi Audio ZP3 is packed with features that make it a versatile centerpiece for any audio system.

Comprehensive Connectivity

The rear panel of the ZP3 showcases its impressive connectivity options:

• Inputs: 2x RCA stereo inputs and 1x balanced XLR input
• Outputs: RCA stereo output, balanced XLR output, and dedicated subwoofer output
• Trigger Connections: 12V trigger input and output for synchronizing power with other components

The inclusion of both balanced XLR and unbalanced RCA connections for both input and output is a standout feature at this price point, providing flexibility and higher performance for those with compatible equipment.

The trigger connections are a thoughtful addition, allowing the ZP3 to be part of an automated system where turning on one component can power up the entire chain – a feature typically found on more expensive equipment.

Remote Control

The ZP3 comes with a full-function remote control that provides easy access to all key functions:

The remote allows for one-touch input switching and volume adjustment, making it convenient to manage your audio system from your listening position. This is a significant advantage over many budget preamps that lack remote functionality or offer only basic controls.

Adjustable High-Pass Filter

One of the ZP3’s most impressive features is its three-level adjustable high-pass filter. This allows you to filter low-frequency signals from the main outputs (RCA/XLR) while routing bass frequencies to the dedicated SUB-OUT.

The filter can be set to different cutoff frequencies (off, 80Hz, or 120Hz), allowing you to optimize the crossover point between your main speakers and subwoofer. This feature is properly implemented and works exceptionally well in practice.

In case you are wondering where the switches are located, they are in the bottom right corner of the underside of case:

Tone and Balance Controls

The ZP3 provides bass and treble adjustment knobs on the front panel, allowing for ±6dB of treble adjustment and ±12dB of bass adjustment. There’s also a tone bypass switch that removes these adjustments from the signal path when not needed – a purist touch that’s appreciated.

The balance control allows for fine-tuning the left/right channel balance, which can be crucial for achieving optimal imaging in asymmetrical rooms or compensating for speaker placement.

Swappable Op-amp

As noted in the manual, the ZP3 features a swappable op-amp design, allowing enthusiasts to experiment with different op-amps to fine-tune the sound to their preferences. This level of customization is rare in this price range and will appeal to those who enjoy tweaking their systems for optimal performance.

Sound Impressions

The Fosi Audio ZP3 delivers clean, transparent sound that allows the character of your sources and amplification to shine through. As a preamplifier, its primary job is to control volume and switch sources without coloring the sound, and it accomplishes this admirably.

Testing Setup

For this review, I tested the ZP3 in an almost complete Fosi Audio stack including:

• Fosi Audio ZP3 Preamplifier
• Pair of Fosi Audio V3 Mono amplifiers
• Fosi Audio SP601 speakers
• Fosi Audio ZA3 as a source
• Fosi Audio Luna turntable (via a phono preamp)
• Kef Kube 10 subwoofer

Bass

The bass performance through the ZP3 is clean and articulate. When using the high-pass filter to integrate with the Kef Kube 10 subwoofer, the crossover was seamless, allowing the SP601 speakers to focus on mids and highs while the subwoofer handled the low frequencies.

The bass control on the front panel provides useful adjustment without introducing distortion, allowing you to tailor the low-end response to your preference or to compensate for room acoustics.

The high-pass filter is particularly effective, offloading bass duties to the subwoofer in a way that enhances overall system performance. With the filter set to 80Hz, the SP601 speakers were freed from the strain of reproducing deep bass, resulting in cleaner, more dynamic performance in the midrange and treble, while the Kef subwoofer handled the low frequencies with authority.

Midrange

The midrange reproduction is neutral and transparent, allowing vocals and instruments to come through with natural timbre and presence. There’s no noticeable coloration or emphasis, which is exactly what you want from a high-quality preamplifier.

Female vocals in particular had a lifelike quality, with subtle details and inflections preserved beautifully. Piano notes had the proper weight and decay, demonstrating the ZP3’s ability to maintain the integrity of complex harmonic structures.

Treble

The high-frequency performance is extended and airy without any harshness or brightness. Cymbals and high-hat details are rendered with natural texture and shimmer. The treble control provides subtle but effective adjustment when needed, without introducing artifacts.

The clarity in the treble region helps create a sense of space and air around instruments, contributing to the overall sense of realism in the presentation.

Soundstage and Imaging

The ZP3 creates a wide and deep soundstage with precise imaging. Instruments are placed with excellent specificity within the soundstage, creating a three-dimensional presentation that enhances the listening experience.

The balance control proves particularly useful for fine-tuning the center image, allowing for precise adjustments that can significantly improve the spatial presentation of recordings.

Specifications and Measurements

The Fosi Audio ZP3 boasts impressive technical specifications:

Dimensions and Physical Specifications

• Dimensions: 239mm × 164mm × 54mm
• Channel: 2.0

Connectivity

• Input: RCA x2, XLR
• Output: RCA, XLR, SUB

Audio Controls

• Bass and Treble Control Range: Treble: ±6dB, Bass: ±12dB
• Frequency Response:
  • XLR/RCA: 20Hz-20kHz (±0.2dB), 80Hz-20kHz (±0.2dB), 120Hz-20kHz (±0.2dB)
  • SUB: 20Hz-200Hz (±0.2dB)
• Input Voltage Range: AC 110-240V

Balanced Output (XLR) Performance

• SNR: ≥ 112 dB
• Dynamic Range: ≥ 112 dB
• THD+N: ≤ 0.0007%
• Noise Floor: ≤ 6μV

Single-Ended Output (RCA) Performance

• SNR: ≥ 115 dB
• Dynamic Range: ≥ 115 dB
• THD+N: ≤ 0.0008%
• Noise Floor: ≤ 4μV

Measurements

For those interested in objective performance metrics, the Fosi Audio ZP3 was thoroughly measured by Amir at AudioScienceReview. I encourage readers to check out the full review at AudioScienceReview.

The balanced output measurements show excellent performance:

The RCA output measurements are also very good, though slightly behind the balanced performance:

These measurements confirm the ZP3’s excellent performance, with very low distortion and high signal-to-noise ratios. The frequency response is admirably flat across the audible range, indicating neutral, uncolored sound reproduction.

Volume Control Behavior - The One Weakness

Despite its many strengths, the ZP3 has one notable weakness: the behavior of its volume control. Unlike many digital volume controls that maintain consistent settings across inputs, the ZP3’s volume setting can be difficult to predict when switching between inputs.

This becomes particularly problematic in households with children who might play with the knobs, or even for adults who might accidentally leave the volume set very high on an unused input. When switching to that input later, you could be greeted with unexpectedly loud audio that could potentially damage speakers or hearing.

The issue stems from the difficulty in knowing what the actual volume is set to at any given time. While the physical position of the knob provides a visual cue, it doesn’t always accurately reflect the actual output level when switching between inputs.

This is a significant oversight in an otherwise excellent product, and it’s the primary reason the ZP3 receives a 4-star rather than a 5-star pragmatic rating. Users should be aware of this behavior and take care when switching inputs, especially in households with children.

Rating Explanation

The Fosi Audio ZP3 earns a solid 4-star pragmatic rating, falling just short of perfection due to the volume control behavior issue mentioned above. However, it excels in nearly every other aspect:

• Build Quality: Excellent construction with high-quality materials and a premium feel
• Features: Outstanding feature set with multiple inputs/outputs, high-pass filter, remote control, and tone adjustments
• Connectivity: Exceptional connectivity options including balanced XLR and RCA connections
• Performance: Clean, transparent sound with excellent measurements
• Value: Delivers features and performance typically found in much more expensive preamps

The ZP3 is ideal for:

• Audiophiles looking for a feature-rich, high-performance preamp on a budget
• Users integrating a subwoofer who need a proper high-pass filter
• Those building a system with multiple sources who need versatile connectivity options
• Anyone who appreciates the convenience of remote control and trigger connections

If the volume control behavior were improved, this would easily be a 5-star product. Nevertheless, it remains an excellent value and a highly recommended component for most audio systems.

Conclusion

The Fosi Audio ZP3 Preamplifier is an impressive piece of equipment that offers exceptional value for money. It combines versatile connectivity, thoughtful features, and excellent sound quality in a well-built package that would satisfy even demanding audiophiles.

The proper implementation of the high-pass filter for subwoofer integration is particularly noteworthy, allowing for seamless blending between main speakers and a subwoofer. The inclusion of balanced XLR connections, trigger inputs/outputs, and a full-function remote control elevates the ZP3 above many competitors in its price range.

While the behavior of the volume control is a legitimate concern that prevents it from achieving a perfect score, it’s a manageable issue that shouldn’t overshadow the ZP3’s many strengths. With a little care and awareness when switching inputs, users can enjoy the excellent performance this preamp has to offer.

For those building or upgrading a home audio system, particularly one that includes a subwoofer, the Fosi Audio ZP3 deserves serious consideration. It offers a level of performance and functionality that typically comes with a much higher price tag, making it a pragmatic choice for budget-conscious audiophiles who don’t want to compromise on quality or features.