Portable EQ &
Headphone Amp

featuring SmartVektor
Full Spectrum Technology

MSRP: $225
Buy the ZO FS

1,089 exhilarating ways to enjoy your music

The Pursuit of Perfection

We worked tirelessly for more than a year to design a product we’re extremely excited to present. Our journey began with the creation of a class-leading headphone amplifier – the perfect foundation for our now patented SmartVektor® technology. So if you're a devout headphone enthusiast, and want the most customizable listening experience in one of the smallest form factors available, look no further than ZOFS.

The Thrill of
Full Spectrum Sound

The thrill of engaging sound is at your fingertips with SmartVektor FullSpec technology. This all-analog EQ features 33 bass and 33 treble levels, giving you a seemingly infinite set of 1,089 combinations for ultimate control over your listening experience.

ZOFS gives you punchier bass, with power and precision surpassing our previous ZO models. In concert with dynamic bass, elevate your sound with 33 levels of sparkling treble to deliver sound like you've never heard before.

Tap into the hidden emotion and fidelity in your music.

Expect the Unexpected

We have totally raised the bar in every aspect of ZOFS. From the extensive sampling and critical evaluation of components, to the meticulous design of ZO’s architecture, everything has been passionately crafted and engineered to give you the best ZO yet.

High Resolution
Volume Control

ZOFS uses a digitally-controlled analog volume control, which is usually only found in hi-end professional audio equipment. It provides more than 200 volume level adjustments at 0.5dB per level, enabling exceptionally smooth and noise free volume changes. With a total of 96dB attenuation (plus mute), precise adjustment is at your fingertips whether you're listening with hard to drive headphones, sensitive IEMs, or with an LOD, and without the need for multiple gain settings.

High resolution volume control
Intuitive user interface

Intuitive User Interface

Get an at-a-glance view of volume, bass & treble settings, while keeping an eye on battery status with the full-color OLED screen. Simply push in the ALPS multifunction switch to toggle through settings and rotate up/down to change levels.

Deceptively Powerful

ZOFS has upped the game when it comes to power. With a voltage output of 9.2 Vpp in combination with 263 mA of current, ZOFS delivers 9x the output power (550mW @ 8Ω) compared to previous ZO models. With this, ZO easily drives everything from sensitive IEMs to high impedance headphones with authority and fullness.

Deceptively powerful

Audiophile Performance

Power Supply Architecture

ZO uses 3 dedicated dual supplies - one each for the amplifier, volume control and SmartVektor systems. This configuration allows fast and smooth delivery of power to the headphones. The true ground referenced amplifier eliminates DC blocking capacitors on the outputs, and a separate LDO regulator keeps all noise from the microprocessor isolated from the analog audio circuits.

High-Performance Op-Amp

The ZO uses the AD8397 op-amp, which is known for its low distortion, high output current and wide dynamic range capabilities.

Ultra-low Noise Components

All components in the audio signal path were specifically selected for their noise suppression and precision characteristics, such as the 0.1% tolerance metal film resistors, film and COG dielectric capacitors.

Solid Foundation

ZO is constructed on a gold-plated, 6-layer PCB, with separate power planes for analog ground, digital ground, and system power. With these low impedance current paths and a fourth layer dedicated exclusively to audio signals, noise and interference are kept at imperceptible levels.

Low Impedance Battery

A Li-Polymer battery with very low internal impedance ensures instantaneous current is always available when power demand is high.

EMI Suppression & Signal Integrity

Every active audio component in the system uses high frequency (LC) bypass filters on the power rails to eliminate EMI. We also use shielded audio jacks with copper alloy conductors and gold-plated contacts.

Big Things Do Come in Small Packages

Couple premium sound with one of the smallest sized headphone amps available, and you've got everything needed for the ultimate portable rig. Plus, the custom, precision machined aluminum enclosure helps reject external electrical interference to lower noise. Are you packin'?

Tech Specs


Dimensions 44.4 x 78.7 x 10.9 mm
Case CNC machined aluminum
Black anodized


Input/Output 3.5mm
Charging Micro-USB


Capacity 600mAh, Li-Polymer
Charge Time < 2 hrs
Playback Time 10-12 hrs
Low Batt Fuel Gauge 8 levels

In the Box

  • ZOFS
  • Mini 3.5mm stereo cable
  • Micro-USB charging cable
  • Quick start guide

Made in the USA

Under the Hood

Max Input 2.0Vrms
Input Impedance 10 kΩ
Output Impedance 0.45Ω
Max Output Voltage 6Vpp @ 8Ω
8.8Vpp @ 300Ω
Max Current Output 263mA @ 8Ω
11mA @ 300Ω
Power Output 550mW @ 8Ω
32mW @ 300Ω
Single Gain Mode From -87 dB to 18 dB
Attenuation -87dB @ 0.5dB steps (plus mute)
Volume Steps 210
Bass 33 selectable center frequencies from
13.68dB @ 25Hz to 0.42dB @ 90Hz
(0.42 dB/step)
Treble 33 selectable center frequencies from
5.94dB @ 3kHz to 0.18dB @ 20kHz
(0.18 dB/step)

Denotes a new/improved feature from ZO2

Experience the Exhilaration