Some sounds cannot be digitized away.

They live in vinyl grooves, analog tape oxide, and the subtle air a studio mic captures at the moment of performance.

SGL7 exists to deliver those sounds — unaltered, uncolored, uncompromised — to your listening room.

Before we talk about what SGL7 does, let us acknowledge what most preamplifiers fail to do.The audio industry has long accepted certain compromises as inevitable — channel imbalance at low volumes, audible switching transients, power‑supply noise bleeding into the signal path. These are not defects of any particular brand; they are limitations embedded in conventional designs.

SGL7 was conceived to challenge those limitations — not by adding features, but by rethinking every fundamental design decision. · What if volume attenuation did not rely on mechanical wear? · What if digital control circuits never touched the analog power supply? · What if switching between sources produced no audible transient? These are the questions that guided every stage of SGL7's development.

These are not vanity numbers. They are the foundation of what you hear.

12‑Bit R‑2R Relay Attenuation：

The conventional carbon‑film potentiometer relies on a mechanical wiper sliding across a resistive track. Over time, the wiper wears. Channel tracking — especially at low listening levels — drifts. This is not a quality issue; it is a structural limitation.

SGL7 replaces mechanical sliding with precision switching. A 12‑bit R‑2R resistor network, controlled by sealed relays, provides 4,096 discrete attenuation steps.

The listening experience: volume changes feel like silk sliding across your fingertips — every step is exactly where it should be.

Dual‑Isolated Linear Power Supply

Noise in an audio system rarely originates in the amplification stage. More often, it enters through the power supply — specifically, when digital and analog circuits share a common power source. SGL7 employs a fully isolated dual‑rail linear power supply:

The two paths are physically separate from the transformer secondary onward. High‑frequency switching noise generated by digital circuits never reaches the analog domain.

Measured noise floor: 3 µV — a background against which micro‑dynamics, hall ambience, and low‑level detail emerge with uncommon clarity.

In your listening room: at 1AM, volume at maximum, ear to the tweeter — you hear nothing but the room’s still air.

POP‑Free Operation

An MCU‑driven global control system manages all relay sequencing during power‑on, power‑off, and input switching. The timing sequence ensures that output stages are connected and disconnected in the correct order — eliminating audible transients that could otherwise stress downstream amplifiers and loudspeakers.

· Power‑on: power amp first → delay → preamp output · Power‑off: preamp output first → delay → power amp · Input switching: mute → switch → unmute

Silent. Smooth. Protective. Your amplifier and speakers deserve that respect.

CNC‑Machined Chassis

SGL7's chassis is not folded or welded sheet metal. It is precision CNC‑machined from a single billet of aerospace‑grade aluminum.

· Monocoque construction — no seams, superior rigidity, excellent vibration damping · Multi‑cavity isolation — independent compartments for power supply, analog amplification, and control circuitry · 430 mm standard width — professional form factor for any rack · Net weight: 8 kg — pick it up once. You will understand.

The foundation of a great sound starts at the enclosure.

Gain Settings — Matching the Source

Gain adjustment ensures optimal level matching for sources with different output voltages.

Guidance: Set gain when you first connect a source, then leave it. A properly matched gain stage ensures that different sources produce roughly the same playback level at the same volume‑knob position — eliminating sudden level jumps when switching inputs and allowing the volume control to operate within its optimal range for fine adjustment.

Voicing Presets — Defining the Sonic Character

The three voicing presets are not conventional equalisation curves. They adjust the operating behaviour of the analogue amplification stage — specifically, the feedback network depth and the biasing conditions of critical gain stages — to achieve a holistic shift in sonic character. Signal integrity and distortion figures remain unchanged; only the presentation evolves.

The effect is subtle in measurement but musically significant: a shift in the balance between harmonic content, transient behaviour, and spatial presentation that alters the relationship between the listener and the performance.

Neutral Balanced

Description: Reference‑grade transparency, neutral, open, precise imaging, natural transients. Recommended for: Orchestral, chamber, piano, acoustic, well‑engineered albums. Pairing: Transparent speakers, neutral amp, quality source. Better balance ---greater benefit.

Warm Vocal

Description: Rich midrange, full‑bodied, warm, intimate, immersive. Recommended for: Vocal‑centric pop, jazz, folk, blues, vinyl, remastered old recordings. Pairing: Tames bright/lean/analytical systems. Best with tube amps or full‑range speakers.

Dynamic Analytical

Description: Extended dynamics and transient clarity, fast, open, highly detailed, layered, tense. Recommended for: Late‑Romantic, film scores, complex rock, concertos, piano sonatas. Pairing: Requires a resolving system — amps and speakers that track dynamic contrasts without compression to unlock full potential.

Advanced Customization: User — Replaceable Op-Amps (Single or Dual)

Beyond the three factory voicing presets, the SGL7 offers room to experiment: its internal op‑amps are socketed and user-replaceable, supporting both single and dual types.

You can swap in op-amps of different brands and sonic characters to suit your listening preferences:

· Want a warmer, richer tone? Try awarm-sounding op-amp.

· Prefer a more neutral, transparent presentation? Use a monitor-grade op-amp.

· Looking for greater dynamic resolution? Install a high-speed op-amp.

Changing an op-amp is like changing the character of the sound.

With three voicing presets plus user-replaceable op-amps, the SGL7 goes from simply "sounding good" to becoming "your sound."

Note: Always disconnect power before replacing op-amps and take proper ESD precautions. Pay attention to op-amp orientation and pin alignment. If you are not experienced with this type of work, we recommend having a qualified technician perform the replacement.

Combining Gain and Voicing — A Framework for System Tuning

Gain ensures each source enters SGL7 at the optimal level — preserving dynamic headroom and SNR regardless of output voltage.

Quick Reference Guide — Find Your Sound

Technical Note on Voicing Implementation

The voicing presets are implemented entirely within the analogue domain — no digital signal processing (DSP) is involved. Each preset adjusts the operating parameters of the discrete analogue amplification stage, including local feedback depth and bias conditions. This approach preserves the signal integrity and inherent linearity of the analogue path while enabling meaningful tonal variation.

Frequency response variation across presets: < 0.5 dB at any frequency. The audible differences derive primarily from harmonic structure, transient behaviour, and spatial presentation — not from frequency response manipulation.

Measured performance (all presets) :

· THD+N: < -116 dB @ 1kHz A‑wt · SNR: < -126 dB @ 1kHz A‑wt · Crosstalk: < -140 dB @ 10kHz

The voicing controls do not compromise the measured performance of the SGL7. They are a refinement of character, not a trade‑off in quality.

Control Interfaces

SGL7 offers three control paths, allowing the user to choose the most natural interaction method for any situation:

Hold the encoder knob ~8s to start a system reset — all settings revert to factory defaults after a 10s countdown.

Display & Parameter Memory

The front panel features a 3.7‑inch medical‑grade IPS LCD with LED backlighting:

Each of the five analogue inputs independently stores its own volume, gain, and voicing settings. These parameters are retained after power‑off — upon restart, the unit returns to its previous state without user intervention. Switch sources. SGL7 recalls your preferences. Power off? Settings persist.

Intelligent Standby

When muted or left idle for 90 seconds, the unit initiates a ten‑second standby countdown before entering low‑power standby mode. The power indicator pulses red during standby and returns to steady orange upon wake‑up. Any button press — on the front panel or the remote — awakens the unit instantly.

Understands your listening rhythm. Cares about your electricity bill.

Inputs

XLR Balanced × 2 — DACs, streamers, CD transports RCA Unbalanced × 3 — phono stages, TVs, gaming consoles, Bluetooth receivers

Outputs

XLR Balanced × 2 — main amplifier (or bi‑amping with two power amps) RCA Unbalanced × 1 — active subwoofer (2.1 system ready)

Pure stereo, desktop monitoring, or 2.1 home theatre — SGL7 covers it all.

Trigger — One Button, Entire System Awake

When the master device powers on, a trigger signal is sent to the SGL7's Trigger In, which powers on the SGL7 and forwards the signal via Trigger Out to the power amplifier, which then powers on as well.

One press. Everything wakes.

Rear Panel Overview

Trigger Input / Output — 3.5 mm mono jack, 5V – 12V DC Ground Binding Post — common chassis ground reference; reduces ground‑loop interference Voltage Selector Switch — 110V / 220V AC mains operation (factory‑fitted dual 1A fuses)

IEC Power Inlet — integrated switch and fuse holder for a clean rear‑panel layout

SONCOZ has been designing analogue audio electronics for years. Through each generation, one principle has remained constant:

Analogue design is not about component selection alone. It is about the precise placement of every resistor, the routing of every trace, the location of every ground return — and the cumulative effect of these decisions on the signal path.

SGL7 is not a specification‑driven product. It is a preamplifier built for extended listening — for those moments when the system disappears and only the music remains. When you press play, and the music flows — the engineering decisions we have made, the measurements we have verified, and the listening tests we have conducted — all converge on a single outcome:

The recording, delivered as intended.

"After switching to SGL7, I realised how much detail my previous preamp had been masking." — Mr. Zhang, Beijing

"The background is truly black. Even at maximum volume, there's almost no noise." — Mr. Li, Shanghai "The three voicing modes are clearly distinguishable. Not some 'audiophile imagination.'" — Mr. Chen, Guangzhou (Real user feedback, collected independently.)