FiiO K13 R2R Control

Desktop controller for FiiO K13 R2R DAC/AMP with full EQ management and AutoEQ integration.

Table of Contents

• About
• Features
• Requirements
• Installation
• Usage
• Technical Details

About

FiiO K13 R2R Control is a native desktop application for controlling the FiiO K13 R2R DAC/AMP via USB HID. Built by reverse-engineering the FiiO Control web app, it communicates directly with the device over USB — no Bluetooth required.

The app provides a full 10-band parametric EQ editor, preset management, and one-click headphone correction from the AutoEQ database.

Features

• 10-Band Parametric EQ — Full control over frequency (20Hz–20kHz), gain (±12dB), Q factor (0.1–10.0), and 7 filter types (Peak, Low Shelf, High Shelf, Band Pass, Low Pass, High Pass, All Pass)
• Live Frequency Response — Real-time visualization of the EQ curve as you edit
• Preset Management — Switch between factory presets (Jazz, Pop, Rock, Dance, R&B, Classic, HipHop, Retro, sDamp) and 10 user-editable slots with custom names
• AutoEQ Integration — Browse thousands of headphone correction profiles, preview the curve, and apply with one click
• Global Gain Control — Adjust the overall EQ preamp level
• Direct USB Communication — No BLE, no middleware — raw USB HID interrupt transfers via rusb
• Save to Device — Persist settings directly to the K13 R2R's onboard memory

Requirements

• OS: Linux (tested on Fedora 43). Windows/macOS support is possible but untested.
• Device: FiiO K13 R2R connected via USB
• Build tools: Rust 1.70+, Node.js 18+, Bun

USB permissions: You may need a udev rule to access the device without root. Create /etc/udev/rules.d/99-fiio.rules:

SUBSYSTEM=="usb", ATTR{idVendor}=="2972", MODE="0666"

Then run sudo udevadm control --reload-rules && sudo udevadm trigger.

Installation

From Source

git clone https://github.com/SmookeyDev/fiio-k13-control.git
cd fiio-k13-control
bun install

Build dependencies

sudo dnf install rust cargo webkit2gtk4.1-devel libusb1-devel libappindicator-gtk3-devel

Development

bun run tauri dev

Production build

bun run tauri build

Usage

1. Connect the K13 R2R via USB and launch the app
2. Click Connect — the device name appears in the sidebar
3. Edit EQ bands by selecting a band and adjusting frequency, gain, Q, and filter type
4. Switch presets from the dropdown — factory or user slots
5. Save your settings to any of the 10 user preset slots
6. For headphone correction, go to AutoEQ, search your model, and click Apply

Presets

• Factory (read-only): Jazz, Pop, Rock, Dance, R&B, Classic, HipHop, Retro, sDamp-1, sDamp-2
• User (editable): USER 1–10, with renameable labels
• Bypass: Disables EQ processing entirely

Technical Details

USB HID Protocol

The K13 R2R communicates over USB HID on interface 3 using interrupt transfers (EP OUT 0x02, EP IN 0x83, Report ID 0x07).

Packets follow a fixed structure:

TX: [0xAA] [DIR] [00] [LEN] [CMD] [SUB] [DATA...] [zero-padded to 64 bytes]
RX: [0xBB] [DIR] [00] [LEN] [CMD] [SUB] [DATA...]

• DIR — 0x01 = GET (read from device), 0x02 = SET (write to device)
• CMD — Command ID (e.g., 0x07 = EQ band, 0x09 = preset selection)
• SUB — Sub-command or band index

Data Encoding

• Frequency: 2 bytes big-endian, value in Hz
• Gain: 2 bytes — [sign_byte][abs_value × 10], where sign 0x01 = negative
• Q Factor: 2 bytes — [integer_part][decimal × 10]
• Filter Type: 1 byte — 0=Peak, 1=LSC, 2=HSC, 3=BPF, 4=LPF, 5=HPF, 6=APF

Architecture

┌─────────────────────────────┐
│  Svelte 5 Frontend          │
│  (Runes + SvelteKit)        │
│         │                   │
│    invoke() ──► Tauri IPC   │
└─────────┬───────────────────┘
          │
┌─────────▼───────────────────┐
│  Rust Backend               │
│  commands.rs → device.rs    │
│         │                   │
│    rusb ──► USB HID         │
└─────────┬───────────────────┘
          │
┌─────────▼───────────────────┐
│  FiiO K13 R2R               │
│  (Interface 3, EP 0x02/83)  │
└─────────────────────────────┘

AutoEQ Pipeline

1. Fetches the AutoEQ INDEX.md and parses the headphone list
2. On selection, fetches the ParametricEQ.txt for that model
3. Parses preamp, frequency, gain, Q, and filter type for each band
4. Writes each band to the device via USB HID and saves to the selected user preset slot

License

This project is licensed under the MIT License - see the LICENSE file for details.