Soncoz SGP-1

The Chinese power amp that holds its own

Disclaimer: This is a purchased review unit. Neither Soncoz nor any other company had any influence over this review.

For years, "made in China" in hi-fi meant budget gear: functional and decent value, but not something you'd put next to a Benchmark or a Bryston and expect it to hold its own. That reputation is shifting, and the Soncoz SGP1 is a good example of why.

Soncoz is a small brand out of Chengdu, China, with no decades of pedigree and no marketing budget to match the industry leaders. What it has built is a €1,390 power amplifier that, in hand, feels like it belongs in a much higher bracket: a solid chassis, tight fit and finish, and nothing that screams budget the moment you pick it up.

That's the more interesting story here. Not whether the SGP1 beats any one specific rival, but what it represents: a brand building gear that competes on merit with the big names, at a price that undercuts them outright. Soncoz is one of an increasing number of Chinese manufacturers leaving the old label behind.

This review is about finding out whether the SGP1 backs that up.

Build & design

Out of the box, the SGP1 makes it clear it isn't playing in the same league as most power amps under €1,400. Available in black or silver, it measures 350 x 260 x 125 mm and weighs 8.8 kg, more compact than you'd expect from a spec sheet promising 240 W into 4 ohms. The two large side-mounted heatsinks, each machined from a single block of aluminum, recall the Benchmark AHB2, though the overall look is more minimalist. Nothing about the fit and finish suggests corners were cut to hit the price. The only blemish on my unit was a small dent in one of the heatsink fins, which could be down to shipping, its life as a review unit, or a slip in quality control.

The front panel is dominated by a pair of analog VU meters. They're not just for show: they're responsive and easy to read, tracking the music in real time rather than lagging behind it. My one design quibble is the logo, which appears both engraved in the front panel and on the VU meters, once more than it needs to. The only control is the power button, which has a very satisfying feel and click.

Around the back, things stay deliberately simple. Inputs are balanced XLR only, left and right, with no RCA option. A 3.5 mm TRS jack handles trigger I/O, and power comes in through a standard IEC inlet with a 230 V/115 V voltage selector.

Day to day, it's unfussy. Aluminum-and-rubber feet isolate it from vibration, and cooling is passive, relying on perforated vents top and bottom plus the side heatsinks. The amp runs hot, though never alarmingly so. Thermal protection shuts it down above 65 °C, but that never happened during my testing, and the design allows stacking without thermal issues.

Under the hood

Inside, the SGP1 is a fully discrete Class AB design, the result of what Soncoz describes as three years of development. The output stage uses four pairs of NPN/PNP transistors per channel in a parallel push-pull arrangement, a brute-force approach to keeping the amplifier comfortable into difficult loads. At the heart of the circuit sits a patented driver module which, according to Soncoz, keeps the output stage operating in its linear region and eliminates crossover distortion regardless of signal level or load. That is the classic weak point of Class AB designs, so it's a bold claim, and one worth checking against the measurements.

The numbers on paper are ambitious for the price. Soncoz rates the SGP1 at 2 x 120 W into 8 ohms and 2 x 240 W into 4 ohms, with THD+N below 0.0003% and a signal-to-noise ratio of 130 dB (A-weighted, at full rated output). If those figures hold up, they put the SGP1 in territory usually reserved for amplifiers costing several times more. Gain is fixed by the internal discrete op-amp stage and can't be adjusted, which is worth knowing when pairing it with a preamp or a DAC with volume control. Soncoz quotes an output impedance of 10 milliohms, giving a damping factor of around 800 into 8 ohms, which on paper promises a very firm grip on the woofers.

One genuinely unusual choice for a Class AB amplifier of this power: there is no big toroidal transformer inside. The SGP1 runs on a custom LLC high-frequency switching power supply, rated at 1,200 W peak and over 850 W continuous. That explains the fast warm-up, and why 8.8 kg is a relatively modest weight for this much power. It also goes against the received wisdom that serious Class AB amps need heavy linear supplies. Whether that choice has audible consequences is exactly the kind of question the rest of this review is for.

What the measurements say

We don't have a measurement bench at HiFiHub yet, so I rely on the measurements Audio Science Review published in 2023, which in my opinion are the most thorough independent data available for the SGP1, alongside those SONCOZ publishes on its website.

The standout figure is SINAD, which compares the music signal with everything the amplifier adds to it, distortion and noise combined. The SGP1 measured 106 dB, among the best results recorded and well above average. In plain terms, it adds about twenty times less unwanted residue than a typical amplifier. For a Class AB design at this price, that's remarkable.

Soncoz's own claims mostly hold up. The claimed 240 W into 4 ohms measured at 242. Into 8 ohms the amp delivered 111 W per channel with both channels driven, just under its 120 W rating. The distortion claim of -110 dB is met into 8 ohms and missed by only a few dB into 4 ohms. Noise measured 125 dB against a claimed 130 dB, but Soncoz quotes an A-weighted figure, which usually reads a few dB better, so the two agree closely. Spec sheets in this price range are often optimistic, so it's refreshing to see one you can mostly take at face value.

A few other results matter in daily use. Frequency response is ruler flat, within 0.02 dB from 20 Hz to 20 kHz and identical into 4 and 8 ohms, which suggests the amp's tonal balance won't shift with the speaker you pair it with. The noise floor is low enough that the amplifier adds no audible hiss of its own. And the claim that it reaches full performance in under a minute checks out: distortion is essentially stable from the moment it's switched on.

The only real weak spot was higher distortion at 20 Hz at high output. Soncoz traced it to the power supply and says it has since been fixed, and even before the fix it stayed at a level I wouldn't worry about.

In short, the SGP1 measures with the best of them, and the numbers on the box can largely be trusted.

Test system

For this review, the SGP1 replaced the amplifier in my main system, a setup in the same price range. A WiiM Ultra streamer sends the digital signal over USB to a Luxsin X9 DAC, which also handles volume and feeds the SGP1 over XLR. The speakers are my KEF R3 Meta, a three-way bookshelf design with a 4 ohm nominal impedance and modest sensitivity. They aren't the most demanding load, but they clearly reward an amplifier with real power behind it.

Listening impressions

My first impression was of an amplifier that stays out of the way. It sounds transparent, letting the character of the DAC and the speakers come through rather than imposing its own. If it leans anywhere, it's toward a slight warmth, just enough to make long sessions comfortable without softening detail. Overall, I'd call it a neutral amplifier with a touch of body.

Its real strength is power. The R3 Metas never sound like they're fighting the amplifier. As the volume goes up, nothing hardens or compresses: the speakers just get louder and keep their composure, with no strain on peaks and no sense of the system running out of breath. That headroom shows most clearly in how the SGP1 handles dynamic range, and two tracks made it obvious. "Why So Serious?" from Hans Zimmer and James Newton Howard's Dark Knight score and Dire Straits' "Private Investigations" both swing from near silence to full force. Through the SGP1, those swings land with real impact. The quiet passages stay clean and detailed, the peaks hit hard without turning harsh, and the jump from one to the other is fast and precise.

The same reserve translates into control, and "2049" from Hans Zimmer and Benjamin Wallfisch's Blade Runner 2049 soundtrack shows it best. The track is built on huge, deep synth bass that keeps building and pressing into the room, the kind of material where bookshelf speakers often turn boomy and blur everything together. With the SGP1 in charge, the R3 Metas keep the low end tight and defined. Each wave of bass has a clear start and stop, the texture inside those low notes stays audible, and the rest of the mix never gets buried. That grip carries through the whole frequency range, so even busy passages stay easy to follow.

The neutrality and control also pay off in imaging. The R3 Meta's Uni-Q driver already images with real precision, and the SGP1 takes it a step further. Pink Floyd's "Money" is a good example. In the opening loop of cash registers and coins, each sound sits in its own clearly defined spot across the stage, with clean space between them. When the band comes in, the instruments stay just as well separated, and the stage holds together as the track builds. Because the amplifier adds nothing of its own and keeps the drivers under tight control, nothing blurs the edges of the image.

The end result is that the R3 Metas get to show what they're actually capable of. With a weaker amplifier, you hear the speakers within the amp's limits. With the SGP1, the speakers set the limits.

Against the competition

I don't have another power amplifier on hand for a direct listening comparison, so this section looks at what you get for your money: performance, features, and the brand behind the product.

The obvious reference is the Benchmark AHB2, which many consider the standard for clean, transparent amplification. On the bench it's still ahead, with even lower noise and distortion. It's also more flexible, with three gain settings to match different sources and a bridged mono mode if you ever need more power. In stereo, though, the SGP1 holds its own on power, and it costs roughly a third of the price: around €1,390 against around €4,000.

Where established names like Benchmark and Bryston really pull ahead is their track record. Benchmark has been around since the 1980s and Bryston since the 1960s, and both have a reputation for gear that lasts. Bryston is confident enough to back its analog products with a 20-year warranty. Soncoz was founded in 2019, and the SGP1 only launched at the end of 2022, so there's no long-term reliability record yet. I haven't come across a pattern of failures, but the number of owners is still small, and buying one means a certain leap of faith.

That makes where you buy it important. Buying from an overseas webshop usually means one year of warranty, and possibly shipping the amp abroad if something goes wrong. European dealers offer two years, the same warranty Benchmark gives buyers outside North America. For the price, I think the SGP1 is well worth considering, as long as you buy it from a local dealer who can handle warranty claims.

Verdict

The SGP1 set out to show that a small Chinese brand can build an amplifier that competes on merit, not just on price, and it succeeds. It's beautifully built, shows off state of the art measurements, and in my system it gave the KEF R3 Metas all the power and control they could use, with a neutral, transparent sound and just a touch of warmth.

It's for anyone who wants a serious power amplifier without paying a big-name price. It makes the most sense if you already have a balanced source with volume control, such as a DAC with a preamp output, and speakers that reward a powerful amp.

It's less suited to you if your sources are RCA only, since the SGP1 only accepts XLR, or if you need adjustable gain. It also draws up to around 70 W at idle and runs hot, but since it reaches full performance almost instantly, switching it off between sessions costs you nothing. And if a long track record matters more to you than the price difference, an established brand remains the safer choice.

The second-hand market makes the SGP1 even more interesting, if you can find one. Resale value for a newer brand is often lower than for an established name, which can work in a buyer's favor. Buying used also lowers the stakes of the leap of faith I mentioned earlier.

The SGP1 is convincing proof that made in China and high quality can now go hand in hand.