Technics SU-G700M2 Integrated Amplifier Review
David Price thinks this new mid-price digital integrated amplifier is something special…
SU-G700M2 Stereo Integrated Amplifier
AUD $4,399 RRP
“Our objective is to stop the discussion about digital amplifiers”, says Tetsuya Itani. The Chief Technical Officer at Technics is clearly a man on a mission. It's no secret that amongst the hardcore audiophile community, Class D or “digital” amplification is a dirty word; most purists prefer Class A, or Class AB at the very least. Yet Itani san thinks this is a strange state of affairs. He argues that, as the old saying goes, it ain't what you do but the way that you do it…
“Ken Ishiwata was about ten years older than me,” he tells me. “He once said that when transistor amplifiers came out, people thought they sounded terrible compared to vacuum tubes. This was also my experience with Compact Disc back in 1982. At first the purists said it was bad – but not anymore. Now we have the same thing with digital amplifiers. People say they have a bad sound, but we think we have the knowhow to get a great performance with our full digital technology. We want to show people that this is the case.”
Itani san is hoping that the new SU-G700 mk2 will act as an ambassador for this. He believes that it sounds great on its own terms and needs no excuses made. Indeed he is very proud of the two years of work that his team – comprising eight electronics engineers, four mechanical engineers and five software engineers – have carried out to create this and its bigger brother, the SU-R1000 flagship. Effectively, the G700 mk2 is an R1000 that's shrunk in the wash – a downsized, cost-cut version.
The Technics full digital platform is not just Class D, which is fed with an analogue input signal; instead, this is a full digital amplifier that only accepts digital input signals. Any analogue signals, such as analogue line inputs or from the phono stage, are converted into digital by a Burr-Brown PCM1804 analogue-to-digital converter. It's only at the output stage that it is converted back to analogue. “This is a bespoke, in-house digital design using our JENO Engine (Jitter Elimination and Noise-shaping Optimisation)”, adds Itani san.
This involves a powerful digital jitter reduction circuit that's claimed to eliminate it over the entire audible frequency range. A unique, high-precision PWM (Pulse Width Modulation) conversion circuit is used, which Itani san says optimises the noise-shaping speed, degree, and quantisation number. Speaker Load Adaptive Phase Calibration matches the amp's output to the loudspeaker it is driving, and Technics' ADCT system is said to cancel the only distortion component generated in the output stage. The Battery Driven Clock Generator is claimed to be entirely isolated from any noise or fluctuations in the mains supply.
The new Advanced Speed Silent Power Supply is a very low distortion switching type that's based on that used in the SU-R1000. The switching frequency has been increased from the conventional 100kHz band to the 400kHz band to ensure stable supply of voltage and current, and to reduce adverse effects of modulation noise on audio quality. The Chief Project Engineer Kato san tells me that it took two years to develop. “We tried many devices – over twenty types – with special core materials and special wiring, and worked with outside transformer suppliers. We measured many kinds and sizes, and we wanted one that ran cool and delivered a lot of power.”
Itani san continues:
The sound quality is affected by every part of the amplifier. From the first prototype my colleagues were checking the sound quality, and when we had developed the final stage of the amplifier circuit and the power stage, we were getting very good noise figures; it was extremely silent. Yet we still needed more bass power, and also better microdynamics, so we looked closer at the chassis. We found that even the internal fixings on the amplifier chassis had an effect. Some parts should be isolated and some parts should not – and by working out which, we were able to improve noise performance. This is an example of the accumulated knowledge that we gained from this project. Lots of small changes made a very big change. It was time consuming and frustrating, but worth it.
Of course, the amplifier was designed with noise reduction as a key criterion from the start. The SU-G700 mk2 has three-section construction, with partitions installed between the circuit blocks to eliminate interference. The rigid steel chassis was designed to eliminate sound-degrading mechanical vibration; the inner part is made of 1.2mm thick plate, and the base is 2mm thick. The front panel is made of 7mm thick aluminium plate to resist the effects of electromagnetic noise. The amp automatically shuts down various digital modules if they're not being used – such as the display, analogue and digital interfaces, again to minimise noise. For the PC input terminals, power conditioners with non-magnetic carbon film resistors are fitted; high-quality ruby mica capacitors are specified.
This being a modern, 2022-year amplifier, it naturally features a headphone stage and a phono stage – features that were once bog-standard on integrated amplifiers but for some reason seemed to disappear around the turn of the new millennium. The SU-G700 mk2 improves on its predecessor's phono stage by adding moving coil functionality. Much work has gone into this discrete transistor design that uses very low noise FETs with special shielding to prevent electrical interference. Itani san confesses to me that he thinks it's actually very close in quality to that fitted to the flagship SU-R1000, and adds that, “we have also taken the ground cable directly from the SL-1200G turntables, which is much higher quality.”
The SU-G700 mk2 is extremely well presented. Although made in Malaysia, there is no apparent compromise to the quality of the finish; it's not quite Japanese high end but not far off, and has a much silkier feel in use than any European amplifier anywhere near this price. The front panel is a model of simplicity; although I'm not a big fan of power meters, these are nicely integrated and have switchable/defeatable illumination. The input selector and volume controls have a super-swish action, and the small OLED function display is a great touch. However, you'll need the supplied remote to access the submenus, so don't lose it! A headphone socket completes the front panel line-up; Technics has fitted a good quality Class AA headphone amplifier too.
This is certainly one of the most interesting mid-price amplifiers I have heard in a while. It sounds quite different in some respects to most Class AB amplifiers, and indeed many Class D ones too – so I'm not sure if it's useful to talk in these terms. Instead, it has its own distinct and generally very endearing character that combines an engaging musicality – in good part thanks to its lively, powerful and chewy bass – with great immediacy and detail across the midband. Yet unlike many amplifiers that push everything out at you, there is no sign of tonal brightness whatsoever; indeed, if anything, it's almost too smooth in the treble.
The SU-G700 mk2's sound doesn't fit into any of the normal pigeonholes that we reviewers like to fall back on. It seems very quiet (i.e. noise-free) and smooth compared to many Class AB designs, yet it's far less bland and opaque than most Class D's I've heard. For this reason alone, the distinctive sound of this amplifier makes it well worth auditioning, because you're not getting the usual trade-offs that mid-price amplifiers face. For example, Supertramp's School – a classic piece of early seventies rock – at 24/192 PCM via one of its digital inputs – was quite a thing to hear. This amplifier made it sound big, ballsy, gutsy and expansive; as a result the presentation was dramatic and gripping, yet it wasn't shouty and hard. It had a fine musical flow that was aided and abetted by apparently endless reserves of power.
Indeed, this is the key to the SU-G700 mk2, I think. As always in my reviews, I used a variety of loudspeakers but inevitably ended up with my classic Yamaha NS-1000Ms; they have a highish quoted sensitivity but ask a lot of any power amplifier, and have been known to reduce some to wobbling jellies. This new Technics amp simply had no fear; it drove these speakers with great authority, thumping out vast tracts of bass, and carrying bass transients with absolute ease. So, for example, loud hits of the bass drum kicked like a mule out of the dense mix during the latter parts of the song.
The next fascinating facet of this amplifier is its midband. It offers up a very wide soundstage, almost as if someone has pressed a 'stereo wide' button on an old eighties ghettoblaster. For example, the wah-wah guitar work on School pushed way beyond the plane of my loudspeakers. At the same time, the SU-G700 mk2 doesn't hide all the less prominent instruments in the mix; instead they're all pushed a little forward and out at you. This is a gratifying sensation and gives the sound bite and impact, yet it never comes over as tonally harsh – there's no 'chrome-plated' upper midband that you often get on other such engaging sounding amplifiers.
This makes it easy to listen at high volumes, your family and neighbours notwithstanding. You can really push up the listening levels without getting any nasty clanging or ringing in your ears – and this further heightens the impact of that epic bass power. Rush's Subdivisions was great fun, despite being quite a tonally forward recording that can grate through some amplifiers. Again, there was never any sense of the Technics hiding its light under a bushel, so to speak – it didn't leave instruments at the back of the mix recessed and hard to hear. Everything was served up in front of the listener, on a plate, in easily digestible portions.
So the SU-G700 mk2 is perfect, right? Of course not. Although it punches above its weight, it is no SU-R1000. It simply doesn't give as much insight into the timbre of the instruments as you get from the Technics flagship, for example. Despite being apparently very detailed, this more affordable amp doesn't quite convey the true tonal colour of acoustic instruments and vocals, for example. Things are just a little airbrushed and sepia tinted, to be completely accurate. Yet it certainly doesn't suffer from the grey, steely feel of some Class AB amps I've reviewed over the years; instead, things are just a little too smooth and surgary. For example, the hi-hat cymbal work on Subdivisions didn't quite have the bite, sparkle and shimmer that it deserves.
All the same, the Technics remains great fun to listen to, its many endearing features making every genre of music from jazz to classical very satisfying. Herbie Hancock's Speak Like A Child was lovely, the amp reproducing a cavernous recorded acoustic, inside which the different instrumentalists were fairly accurately placed. I could follow each player with ease, and enjoy the gentle syncopation of Hancock's piano work and the drum kit and double bass. At the same time, the fluegelhorn of Thad Jones and Jerry Dodgion's alto flute were mesmeric, reminding me how special this classic 1968 Blue Note recording is.
Moving to its phono input was a pleasant surprise. Being a diehard vinyl junkie, I am always wary of the idea of running my prized recordings through an analogue-to-digital converter, as this amplifier does. Yet the Technics did a very respectable job with the signal from my Technics SP-15/SME Series V/Lyra Delos vinyl front end. The opening Allegro ma non troppo section of Beethoven's Pastoral Symphony (Berlin Philharmonic, Karajan) showed that this amplifier has strength in depth. The concert hall sounded vast, and the music bounded along in a hurry. Dynamics on crescendos were excellent for an amplifier of this price, too, not least because the MC stage is super-quiet. The SU-G700 mk2 can't match high-end amplifiers for firecracker transients but comes closer than you might expect. The result was moving, engaging and immersive sound that was better than expected at the price.
Such is the quality of the new SU-G700 mk2 that I often forgot I was listening to a mid-price integrated amplifier – as opposed to my normal high-end pre/power – and started scribbling uncomplimentary things in my listening notes. That's how good the Technics is. In absolute terms, it lacks resolution, but it makes up for this with a long list of positives – power, punch, scale, drive, engagement and excitement, yet with little loss of smoothness or civility.
It faces stiff competition – from the likes of the old-school, all-analogue Class AB Exposure 3510 on the one hand and the Class D Marantz Model 30 on the other. Yet this amplifier is good enough to hold its head up in this exalted company and better them both in sheer drive. As such, it's an essential product to audition if you're in the market for an amplifier at or near this price – whatever class it is, or you are!
David started his career in 1993 writing for Hi-Fi World and went on to edit the magazine for nearly a decade. He was then made Editor of Hi-Fi Choice and continued to freelance for it and Hi-Fi News until becoming StereoNET’s Editor-in-Chief.
JOIN IN THE DISCUSSION
Want to share your opinion or get advice from other enthusiasts? Then head into the Message Forums where thousands of other enthusiasts are communicating on a daily basis.
CLICK HERE FOR FREE MEMBERSHIP
Each time StereoNET reviews a product, it is considered for an Applause Award. Winning one marks it out as a design of great quality and distinction – a special product in its class, on the grounds of either performance, value for money, or usually both.
Applause Awards are personally issued by StereoNET’s global Editor-in-Chief, David Price – who has over three decades of experience reviewing hi-fi products at the highest level – after consulting with our senior editorial team. They are not automatically given with all reviews, nor can manufacturers purchase them.
The StereoNET editorial team includes some of the world’s most experienced and respected hi-fi journalists with a vast wealth of knowledge. Some have edited popular English language hi-fi magazines, and others have been senior contributors to famous audio journals stretching back to the late 1970s. And we also employ professional IT and home theatre specialists who work at the cutting edge of today’s technology.
We believe that no other online hi-fi and home cinema resource offers such expert knowledge, so when StereoNET gives an Applause Award, it is a trustworthy hallmark of quality. Receiving such an award is the prerequisite to becoming eligible for our annual Product of the Year awards, awarded only to the finest designs in their respective categories. Buyers of hi-fi, home cinema, and headphones can be sure that a StereoNET Applause Award winner is worthy of your most serious attention.