Technics Versatile Network Audio Amplifier Delivers Surprising Sonic Pleasures*

puts the musical world in the palm of your hand

Japanese conglams re-entering the two-channel audio market have mostly gone with nostalgia-based retro looking receivers. And why not? It’s what they were doing when they exited the market and there seems to be a newfound yearning for them among audio enthusiasts of all ages. Technics makes a few of these too, including the SU-R1000, a $10,000 full featured, "modernized" retro-looking integrated receiver.

Technics has gone the opposite route with its SU-GX70, calling it not a “receiver” but a “Network Audio Amplifier”. Its mind-boggling feature set and versatility are inversely proportional to its limited “knobage”. Though its inventiveness might not boggle the minds of consumers and reviewers more familiar with products intended for this market segment, I'm not among them so count me as seriously impressed with both what the SU-GX70 offers and how it offers it.

The compact brushed chrome paneled device exudes high quality and sports but two knobs (the big one adjusts volume, the small one selects source), yet consider this: in addition to the “usual” inputs— MM phono, aux analog, coaxial and optical digital, USB-B, HDMI-ARC and a LAN terminal—the SU-GX70 also features an FM tuner with presets, Bluetooth connectivity and with either Wi-Fi  or wired Internet connectivity, Internet radio, streaming audio through your local network, or via streaming services to which you subscribe including “direct” connections to Amazon Music, Qobuz, TIDAL (it will decode MQA if you’re so inclined), Deezer, Podcasts and more—a total of 20 inputs you can select using the smaller knob’s positive click through, or via the remote control. You can’t direct-select an input “out of the box” but that’s a not a big deal because you can rearrange the input order to put your faves first. The volume knob has a “serious” feel should you choose it and not set volume by remote.

You can also select a “pure” setting that disables network functionality to reduce noise and deliver improved audio quality. There’s also a headphone jack. The relatively small front panel screen is cleanly laid out and at its bottom are touch sensitive“forward/back” “stop” “play” and “pause” “buttons”. The DAC can decode up to 32 bit/384Hz PCM and DSD512 files including FLAC.

That’s just the start of what’s possible with this versatile piece—not that the “basic” instruction manual offers all of what’s possible, or how to access all of it, or how to set it up or use it, because the basic instructions are sketchy. To become fully informed you must download a detailed PDF file via a QR code kind of hidden on page 4 above the ‘TABLE OF CONTENTS’, which is where impatient minds head when turning to page 4!

Though you can get started without it, to really make full use of the SU-GX70 you should download and use the Technics app (more about it later). With it you can create “shortcuts”, use virtual sliders to adjust balance, bass and treble, select MQA decoding, select absolute polarity (“phase”) of both analog line inputs and the phono input and to the latter add a subsonic filter.

 You can also turn on or off the “pre-amp out” RCA jacks. When you set to “on” you can connect to your subwoofer or use the output as "pre-out" to use the SU-GX70 with an outboard power amplifier.

But wait! There’s more! In a process that’s the reverse of Audyssey (the speaker set-up process used with a microphone to configure a surround sound system), the SU-GX70 includes a system (LAPC or "Load Adaptive Phase Calibration) that as best as I understand it, measures your speaker's phase and impedance response and adjusts to produce ideal impulse response. In other words, it clarifies the amp/loudspeaker partnership.

Technics describes it this way:

Speaker impedance changes with each frequency and a power amplifier is required to drive speakers without being affected by the speaker’s characteristics. However, conventional digital amplifiers are connected to speakers through a low-pass filter at the output stage, so they are even more strongly affected by the speaker impedance characteristics. Also, although the amplitude characteristics of conventional amplifiers due to negative feedback were improved, the phase characteristics could not be enhanced.

We thus developed a speaker impedance adaptive optimization algorithm that performs correction to the ideal impulse response through digital signal processing by measuring the frequency amplitude-phase characteristics of the amplifier with the speakers connected. This technique enables flattening of the frequency characteristics of amplitude and phase, which had previously not been achieved by amplifiers, while also delivering a sound with rich spatial expression.

There’s another set up function that optimizes the sound depending upon where you’ve placed your speakers (close to corners, etc.) and there are other set up possibilities and features, but I’ll stop there, though add that the SU-GX70 includes a full-sized well laid out “old fashioned” remote control featuring actual, not virtual push buttons.

 The Dizzying Set Up

 For initial set-up, including accessing your wireless network and interfacing with your internet connected devices as well as with the known and unknown connected universe, you can use Google Chromecast (built-in) or Apple Home. I have a feeling youngsters will navigate this with far greater ease than I managed. I have Google Chromecast on my Sony Bravia televisions and had no problems getting them online, and otherwise I’m an Apple user but without help I couldn’t get logged into my wireless network using either Google or Apple Home.

I can’t now remember how I eventually got it set up, but I remember it being a multi-step process and with some company help I was logged in and then it was time to write down my passwords and then use them to log into my Qobuz, Amazon Music and TIDAL accounts.

My problems with this part of the process led me to suggest to the Technics powers that it should all be presented—at least to the geriatric set— in well-written prose like telling a story instead of a series of commands especially since there are various presented options, which makes somewhat confusing choosing how and where to turn to get all of this accomplished. If you bother to read that page you'll see that this network receiver is referred to as an "output speaker". I don't think this is Technics' doing, but the vernacular just adds to the confusion.

I'm talking about page after page of this:

Once everything was finally set up and configured, using the SU-GX70 in every conceivable source mode was easy and pleasurable. The conveniences were mighty attractive!

Here's how it looks on the app when you wish to choose a source:

Here's how it looks when you're looking at settings on the app:

More adjustments:

How Qobuz looks via the app:

How Tidal looks:

The Power Infrastructure

 Of course, the compact, approximately 14.5 pound SU-GX70 utilizes a proprietary form of what appears to be a type of Class D amplification that the company developed rather than buying "off the shelf" OEM modules. Technics doesn't call it "Class D" but does refer to its "high speed switching power supply (approximately 130kHz)", so then if not Class D, what is it? It includes Technics' proprietary JENO circuit (Jitter Elimination and Noise-Shaping Optimization) Engine designed to produce precision pulse width modulation (PWM) signal conversion with minimal jitter, so again, if it's not "Class D", what is it? The "D" in Class D doesn't mean "digital" so why does almost everyone, including Technics on its website refer to this as "digital amplification" (Technics calls it a "full digital amp")?

I remember at the dawn of Class D receiving many reader tongue lashings for mistakenly calling Class D "digital". At the time I remember someone promoting the now greatly improved technology as saying "We should have skipped over "D" and gone to "E" or "F" to avoid the confusion." Now it seems we're back to calling switch mode power supplies "digital".

Technics' Bill Voss clarified this in a post-Munich show email:

"SU-GX70 and all modern era (2014 on newer) Technics amplifiers are called Technics full digital amplification.  They are not Class D because Class D at some point must operate in the analog domain, thus a convergence.  Technics full digital design and operation always remains in the digital domain.  Yes, convergence from PCM to PWM but never from digital to analog.  Please see attached white paper where it mentions…“There is a commonly known method called Class-D amplifier, and Technics digital amplifier is often mistaken as Class-D, but strictly speaking, Technics digital amplifier is not Class-D. Class-D amplifiers obtain a PWM signal by comparing a sawtooth wave with the analog input signal by a comparator as shown in Fig.1, and drive an output transistor with it. It seems that the output stage is a switching amplifier configuration, and “D” is mistaken for a digital acronym and is recognized as “digital amplifier = Class-D”, but D of Class-D is Class-A, Class-B, Class-D is used as the one following to Class-C, not digital amplifier = Class-D".

Whatever the methodology, the SU-GX70 outputs, depending upon how it’s measured, either 40W+40W (1kHz, 1% THD, 8 ohms/double that into 4 ohms), or 30W+30W FTC output power). That may seem like very modest power but let me tell you I had no trouble achieving high SPLs in my large living room—and without apparent strain— driving three pairs of very different speakers: the relatively inefficient Aretai Contra 100S, Wilson Tune Tots with LoKe subwoofers and most recently the soon to be reviewed YG floorstanding Talus, which are rated at 89dB efficiency and have a nominal 7 ohm impedance. I doubt anyone buying an SU-GX70 will be pairing it with $14,000 loudspeakers but you could!

Oh, I just realized I've not mentioned the SU-GX70's price: it retails for $1,999.95 and can be had online at some places for $1,499.95. In the world of high performance audio that's a set of modestly priced cables! So how does Technics manage all of this tech and versatility for that price? In great part due to its long-standing "trickle down" policy. Much of what's inside is, in simplified form, what's previously been developed for more costly products. That said, this one features twin power supplies, one for the power amp circuit and one for small signals.

And special attention has been paid to the analog inputs, which use discrete amplifier circuits "redesigned and adapted from the circuit used in the SU-R1000, and the same symmetrical layout has been used. Further, other high-quality audio parts of the same grade as those used in the SU-R1000 have also been adopted, such as low-noise FETs, thin-film resistors, film capacitors, and electrolytic capacitors."

In Use and Sound

 Sources included Qobuz and TIDAL streaming, FM radio, vinyl (for this review from a supplied $1299.99 Technics SL-1500C turntable equipped with an Ortofon 2M Red) and a USB stick plugged into the front panel’s USB input filled with hundreds of vinyl transfers, mostly done on my old Continuum Caliburn turntable/SAT arm set up that always wows audio show listener when the files can be played, which is not always.

Of course, vinyl playback through this system necessitates digitization (at 96/24 resolution with RIAA done in the digital domain). There are many advantages to that accorded to ChannelD’s Rob Robinson whose Lino and other phono preamps can be used either either “live” with standard RIAA or digitally recorded “flat” off the record, with EQ applied in the digital domain during playback. So yes, the SU-GX70 is not for “analog purists” but then neither was this website intended solely for them.

Let's start with what I know best among the sources: the USB stick filled with 96/24 files from vinyl. Happily the SU-GX70 played them back no problem, scrolling the song titles across the front panel screen. These great sounding files delivered through the SU-GX70 had commendable clarity, rhythmic thrust, well-articulated, precisely delivered transients, impressive transparency and detail resolution that would impress even analog diehards. The SU-GX70 has the "rhythm'n'pacing" thing down!

For instance on Neil Young's "When You Dance I Can Really Love" from a minty early pressing of After the Gold Rush, instrumental separation and individual note articulation, like on the piano part played by Jack Nitzsche—particularly one particularly striking and dramatic glissando, had me saying "remarkable!" The guitar "crunch" also impressed. While the SU-GX70's presentation was very different from what I'm used to, I found it equally engrossing and musically legitimate, though the perspective was more the beat than the meat.

The next tune was "Division Street" a track from Nick Culp's album Culprit Blues, which I should try to reissue on Liam Records. It's so good! In fact, here's a vinyl rip someone else did. The one I posted is on my former endeavor's channel so check out this one:

Pianist Culp has produced as "Blue Note-y" a non BN record as you're likely to hear. The SU-GX70's rendering from my file was an ear-opener in terms of the tune's rhythmic thrust. The presentation didn't short change the textures to any appreciable degree, making for a seriously entertaining rendering of a familiar track.

Dr. John's great tune "Mama Roux" from an OG pressing of his debut album Gris Gris also produced some great chills as the female background singers chant the title and bass clarinet blasts set the eerie mood. It's also a heavily rhythmic track that the SU-GX70 nailed. Recorded at Gold Star where Phil Spector made his great "Wall of Sound" records and Brian Wilson followed, the sound is vivid. You can almost see the hanging moss. The SU-GX70 poured light on the darkened enterprise, which in some ways added interesting illumination and in other ways, killed the vibe.

Next up was "Try A Little Tenderness" from an original pressing of Live in Europe one of the most exciting live albums ever recorded. Otis is backed by Booker T. and the Mrs and The Memphis Horns and playback never fails to elicit full blown emotional explosions as Otis does his "gotta gotta gotta"s and the crowd goes batshit wild. Here the SU-GX70's forward nature flattened somewhat the venue and lightened, tightened and brightened the picture to its spatial detriment but Redding's voice, usually somewhat buried in murk had a chance to shine.

If you're getting the drift of what this amplifier sounds like you can imagine how great Pat Metheny's rendition of "Pipeline" from his 2011 album What's It All About sounded through it. Every string touch and surprise strum delivered precisely and fully articulated. Microdynamic communication is the SU-GX70's forté and listening to this Metheny track through it was a blast.

Less so "Rocks Off" from an Artisan original Exile.... where the record's intrinsic brightness was pushed too far—but even that track had rockin' rhythmic authority and Ian Stewart's piano and Charlie's rim shots made for much fun listening. One thing's for sure: whatever music you play through it the SU-GX70 will never bore you!

All of the dozens of tracks from the USB stick exhibited a similar tonal balance: an upper midrange/lower treble "presence region" forward push that worked better on some tracks than on others but always made for interesting listening because it revealed new details and/or surprising qualities without becoming excessively bright or "etchy" and at the same time the amp's bottom end was equally firm, articulate and reasonably deep, so the whole sonic package effectively held together.

The FM radio's reception with just a wire taped to the wall was quite good. For instance it had no trouble picking up jazz station WBGO located not far from Technics' Newark headquarters and it cleanly delivered many New York City stations as well. But with that same fast, clean, taut, nimble and clarified sonic signature delivered by the USB stick files.

Switching to vinyl playback, using the supplied SL-1500C/Ortofon 2M Red produced a very similar sonic picture. Did digitization make it sound "digital"? Well even though Class D or however Technics describes it, isn't "digital", the vinyl playback never sounded "warm" and "lush" because the amp didn't do "warm" and "lush". You'd have to add warm, soft speakers or a warm, soft cartridge to perhaps get some of that but then you'd probably diminish somewhat what the SU-GX70 does so well.

The last record I played was the 2009 Bernie Grundman remaster from the original analog tape of Dire Straits debut album (WB 47769-1). It's the one to have if you don't have the Vertigo U.K. original (assuming you like the record!). There are copies for $35 and up on Discogs.If you mostly play rock records and love the sound of electric guitars, you'll dig what this combo does, even though it digitizes the analog. I'm sure with a better cartridge you'd get more from your vinyl but the 2M's delivery was not that far off timbrally from what the stick produced. All of the other records I played delivered that same timbral balance. There were no surprises. In other words: the SU-GX70 has a "sound" and it's a pretty strong one you'll either love or not.

Conclusion

Technics packs a great deal of tech, versatility and sonic performance into this compact, well-built Network Player that obviously benefits from the company's "trickle down" approach to giving customers the most possible for the money spent.

I'm figuring most of our readers are not going for a $1995 or $1500 Network Player as a prime system centerpiece (or maybe I'm wrong) but for an office system? Or to give the kids something great to take to school and add some small bookshelf speakers and maybe a turntable, this would make an interesting and useful choice, especially because its sonic picture holds together really well at low SPLs, which could be particularly useful in a dormitory setting.

About the SL-1500C: online people claiming this $1300 turntable is the equivalent of the $4300 SL-1200G are out of their minds but the SL-1500C is an incredible value and offers build quality few turntables at or near the price can deliver including a built-in defeatable MM phono preamp, defeatable end of side arm lift up and VTA adjustability. it's very different from the belt drives at the same price and sounds different too, but if you have a chance, listen before you buy under $1500.00. Build quality is unrivaled at this price point and as supplied finished in a mute porcelain white, is esthetically very pleasing.

I've not previously played in this sandbox so I can't tell you how the SU-GX70's sonic performance and feature set compares to the competition but given Technics' technical prowess I'd be cautious betting against it. BGO is playing "The Best is Yet to Come" by Shirley Horn and it swung mightily. What's not to like?

* Not everyone will find this kind of sound pleasurable. I do!