Note: for the full suite of measurements from the SoundStage! Audio-Electronics Lab, click this link.
First impressions carry a lot of weight, but they’re not everything. And thank goodness for that, because I didn’t get off on the right foot with Technics’ new Grand Class SU-GX70—an amp I now positively adore. To be fair, most of my quibbles could be filed under the category of “vibes.” As I mentioned in my unboxing blog post, I want a Technics integrated amp to look like a swanky retro throwback, and the SU-GX70 ($1999.95, all prices USD) just evokes any number of nondescript black boxes that have cycled through my system over the years. Worse still, one of my first tactile interactions with the unit was when I gave the volume control a twist only to find that it felt like dragging a wooden spoon through half-crystalized honey.
Of course, the SU-GX70 is much more than a mere volume control. Indeed, it’s much more than merely an integrated amp. Technics calls it the “definitive living room audio center,” and I’ll give them that. It falls firmly into the category of “just add speakers” all-in-one systems, although given the fact that it also rocks an HDMI ARC port, you could also add a TV and some speakers and have a complete A/V system.
The big draw for many will likely be the SU-GX70’s extensive streaming capabilities, with built-in support for Spotify, Tidal, Qobuz, Amazon Music, and Deezer, as well as Chromecast and AirPlay 2 connectivity, and Bluetooth with support for the AAC and SBC codecs. It also boasts a USB-B input, one coaxial (RCA) and two optical (TosLink) S/PDIF inputs, two line-level inputs, a phono input (MM), and an FM tuner (with an included wire antenna). The inclusion of the tuner actually makes it a receiver.
All of that feeds into a power stage built around Technics’ JENO (Jitter Elimination and Noise-shaping Optimization) amp circuitry. Long story short: Digital inputs go straight to the amp’s low-jitter signal-rate converter and then into a delta-sigma PWM converter, whereas incoming analog sources are converted to digital first and then follow the same path. Technics rates the power output of the SU-GX70 as a very conservative 40Wpc (1kHz, 8 ohms, 1% THD, 20kHz LPF) / 80Wpc (1kHz, 4 ohms, 1% THD, 20kHz LPF), with FTC output power (a more stringent standard that indicates continuous long-term output) specified as 30Wpc into 8 ohms or 60Wpc into 4 ohms.
Installing and configuring the Technics SU-GX70
Unsurprisingly, given that the SU-GX70 is a network-connected amp centered on streaming, much of the setup is done via an app. Well, several apps, actually. If you’re relying on the amp’s wireless networking capabilities, you’ll need to use the Google Home app for initial setup. But most of your time will be spent in the Technics Audio Center app, which serves as a remote control for the amp (there’s also a pack-in remote that’s remarkably similar to that of the SU-G700M2), as well as a streaming hub and advanced configuration tool.
One of the things most easily configured from the app is Technics’ Load Adaptive Phase Calibration (LAPC), which adapts to the phase and impedance characteristics of your speakers. If you’ll recall from my review of the SU-G700M2, that integrated amp required the use of the remote control for LAPC setup, meaning if you lost the remote, you wouldn’t be able to run LAPC again. So it’s nice being able to access it from the Audio Center app. The effects are the same, though, so I won’t rehash my findings here. Long story short, with my Paradigm Studio 100 v5 tower speakers, I found that engaging LAPC resulted in more controlled bass performance with very low-end-heavy recordings.
As I mentioned in that review, though, LAPC isn’t room correction. But hang on, because the SU-GX70 has some of that, too, in the form of Space Tune, a feature I’m familiar with from Technics’ brilliant Ottava tabletop music system. At its simplest, Space Tune is an easy way to dial in boundary-gain compensation for quarter-space and eighth-space loading, or even different loading for the left and right speakers. You can also disrobe your smartphone, though, and measure a series of test tones, then apply custom DSP that’s legitimately good room correction. By that I mean that it seems to mostly work to combat standing waves without negatively impacting mid- and high-frequency performance, which is quite the trick for any room correction system.
Such good results are hard-won, though. Which isn’t to say that Space Tune is complicated to configure. Far from it. You simply hold your naked phone in front of your face and wait for the blips and bloops to finish. But despite measuring the background noise in my room as an entirely reasonable 29dB with my own SPL meter before running my measurements, I kept getting error messages along the lines of, “Please reduce the surrounding sounds such as talking and make the room quiet.” After five such errors, for reasons that are wholly mysterious to me, the process worked and that was that.
The app also gives you access to tone and balance controls (the former of which must be turned on first), Pure Amplification mode to turn off the HDMI port and networking capabilities, an MQA decoding on/off setting (I’m assuming that turning it on engages the usual minimum phase low-pass filter), phase inversion toggles for Line 1 and Line 2 as well as the phono stage, subsonic filters for all three of the above, and a ton of other little quality-of-life tweaks.
Throughout the course of my review, I relied on the aforementioned Paradigm Studio 100 v5 towers, connected using pre-terminated Elac Sensible Speaker Cables. My Maingear Vybe PC and iPhone 12 Pro Max were my primary sources, although I couldn’t resist listening to a good bit of FM radio as well. I also plugged in my Audeze LCD-2 cans for some extensive listening, but we’ll get to that in a bit.
How does the Technics SU-GX70 perform?
Let’s not beat around the bramble here. If you’ve followed my reviews for any amount of time and if you saw the amplifier specs listed in the intro, you already know what my primary concerns were in terms of sound quality. If you’re new here, a quick crash course may be in order.
Simply (very simply!) put, 40Wpc into 8 ohms and 80Wpc into 4 ohms is, on paper at least, way more power than most people will ever need with typical loudspeakers in a typical room at typical listening levels. But many an amplifier in this specified range struggles with the impedance swings of even my not-terribly-difficult-to-drive Paradigm speakers. If an amp can’t deliver sufficient current, some songs with plenty of energy in the area around the lowest impedance swings (or steepest electrical phase angles) can start to thin out and sound weak at anything more than moderate listening levels, even if there’s technically enough wattage to hit the desired SPLs.
I have a playlist of tracks handpicked to shine a bright light on such upper-bass/lower-midrange frequencies, the first of which is George Michael’s “Freedom ’90!” from Listen Without Prejudice (24-bit/44.1kHz FLAC, Sony Music CG / Qobuz), a song that I struggle to listen to at anything less than thank-goodness-I-don’t-live-in-an-apartment levels.
Despite being one of the best pop songs ever recorded, though, “Freedom ’90!” is not one of the best-mixed. The bass is just sort of barely sufficient, which means that the song sounds a little thin by default and can turn positively brittle if you lose any of that bass energy. All of which is to say that whether an amp is rated to deliver 30 watts or 300, if it can’t deliver sufficient amperage lickety split, this song is the first coalmine-canary that lets me know.
Through the SU-GX70, it sounded spot-on perfect, even at borderline-dangerous listening levels. With peaks hitting 99dB, I felt like I was missing absolutely nothing in terms of bass. What’s more, I still had 26dB left on the volume knob.
Although I was primarily listening for bass balance, I also couldn’t help but notice how dynamic the sound proved to be. The “Funky Drummer” samples and the iconic piano riff both had exactly the right amount of attack.
At this point, I could have probably abandoned my so-called “Power Supply Stress Test” playlist, but “Jingo” from Santana’s eponymous debut album (24/96 FLAC, Columbia–Legacy / Qobuz) came up in the rotation, and it’s against my religion to pause or skip that song.
“Jingo” lacks for nothing in terms of bass energy. Compared with “Freedom ’90!” it’s incredibly well-balanced, tonally speaking. So if something is lacking in terms of an amp’s ability to push through deep impedance swings, you don’t necessarily hear it as a spectral shift with this track. What you hear is a loss of impact. The bass and larger congas won’t hit you in the chest quite as hard.
I experienced nothing resembling that loss of energy with the SU-GX70. Even at reasonable listening levels, it punched me right in the chest. Again, dynamics were spot on. Transient response was also fantastic, which led to a wonderful soundstage with fantastic image specificity. Add it all together and there was this deliciously holographic quality about the SU-GX70’s delivery of “Jingo” that made me forget my struggles with the Space Tune setup and my overall meh attitude toward the Audio Center app.
But I did remember to do some A/B testing to gauge the performance of Space Tune. And LAPC, for that matter. As with the last piece of Technics kit I reviewed, the effects of LAPC proved to be so subtle as to be difficult to hear with some material. With “Freedom ’90!” I think I heard the tonal balance remain more consistent no matter the listening level. With “Jingo,” though, the effects were unmistakable: the volume control had way less impact on the tonal balance and punch of the music.
With Space Tune, switching back and forth between on and off proved to be easy via the app, and the mute time was short enough to allow for some hair-splitting comparisons. But no hairs needed to be split. The DSP’s impacts on the sound below the Schroeder frequency of my room were substantial and unmistakable.
By this point, I felt pretty confident that I no longer needed my “Power Supply Stress Test” playlist, but it kept throwing bangers at me that I couldn’t resist. Alice Phoebe Lou’s “She” from Live at Funkhaus (24/44.1 FLAC, Alice Phoebe Lou / Qobuz) is one of my favorite tunes from one of my favorite live albums from recent years, and as you might guess from its inclusion on this collection of test tracks, it rocks some really robust bass. But that’s not what grabbed my attention. What drew me in was—again—the dynamics, the punch, the attack of the percussion and the decay of the keyboards. More than that, it was the sense of space, the atmosphere—the precision with which the SU-GX70 rendered every infinitesimal detail.
It was such a delicious mix of nuance and dynamics that I couldn’t resist the urge to plug in my Audeze LCD-2 cans for a bit of personal listening. The SU-GX70 has volume memory for headphones, which is nice. But as I twisted the volume knob to the right, I started to hear some unexpected sizzle in the recording at around the point I was approaching the low end of comfortable listening levels. Given the performance of the amp overall, I initially assumed that this was an element of the mix I hadn’t heard before, but pushing the volume a little harder, I started to get into obvious clipping.
So I switched over to my desktop sound system with my Focusrite USB interface, plugged in my Audeze cans, and cranked the loudness to the high heavens on the same song—and heard none of the distortion I was hearing through the SU-GX70’s headphone output.
What’s going on here? Well, if I really want to dig into a headphone amp’s performance, I have to turn to a track I know more intimately: The Allman Brothers Band’s “Blue Sky” (Eat a Peach, 24/96 FLAC, Mercury Records / Qobuz). Back on the Technics with my Audezes plugged in, with a bit of volume Berry Oakley’s bass line got too saturated, too hot, too bloated, and too prominent in the mix way too quickly.
A swap to my RØDE NTH-100 studio headphones—which are a little more sensitive and a lot less power-hungry—rectified the situation with “Blue Sky” and “She” alike. My Sony MDR-7506 headphones also revealed none of the same distortion or bloat. So what I’m guessing is that the SU-GX70’s headphone output simply can’t muster enough clean power to drive my first-year LCD-2 cans.
On the other hand, I found the SU-GX70’s terrestrial radio reception very good, even with the pack-in wire antenna! There’s one distant regional public radio station I like to listen to occasionally that I couldn’t quite pick up, but that aside, I was able to tune into all of my local favorites clearly and cleanly, with good stereo separation, no static, and very little noise.
What other integrated amps in this price class should you consider?
The Rotel S14 streaming integrated amplifier I reviewed a few months back for SoundStage! Simplifi has recently seen a price drop, bringing its MSRP down near the level of the SU-GX70. It has 80Wpc of output into 8 ohms and nearly doubles that into 4-ohm loads. The Rotel app is about as underbaked as the Technics app, but doesn’t offer nearly as much customizability and the amp has nowhere near as many features, nor does it have an adult-sized headphone output. Nor, for that matter, an HDMI connection.
There’s also the NAD C 389 BluOS-D, which sells for between $1999 and $2099 these days, depending on which way the wind is blowing. This one relies on load-invariant 130Wpc UcD amp modules and features Dirac room correction and BluOS streaming.
Or, if you want something a lot more retro-looking, also with UcD modules and HDMI connectivity, plus BluOS streaming and Dirac room correction, but paired with faux-wood panels and dancing VU meters, the NAD C 3050 (the non-LE version) will set you back somewhere between $1799 and $1899, but good luck getting your hands on one soon if you’re reading this in early 2024. They’re currently out of stock with no expected restock date.
TL;DR: Should you buy the Technics SU-GX70 receiver?
If you don’t have super-thirsty headphones (or if you have a separate headphone amp), don’t need bass management, and don’t mind an iffy app, the Technics SU-GX70 is a very compelling piece. And I know that sounds like a backhanded compliment, but it isn’t intended as such. Because for some people, all that matters is sheer performance, and the SU-GX70 utterly blew me away in that department, at least with my speakers. I feel like Technics is sandbagging the specs on this one, and I have no idea why. Maybe I’ll read Diego Estan’s measurements a month or so after I write this and see that, no, indeed, its specs are spot on. But this performs like an amp with a lot more headroom than what Technics claims on paper.
I feel like this thing could drive a dump truck uphill. Both ways. In the snow. At one point I pushed the volume to -20dB just to see how my speakers would behave, and it got a little dangerous, because I wasn’t picking up on the signs of distress that let me know I’m leaning too hard on the volume knob. My ears just hurt after a while, that’s all.
And yeah, setup can be a bit of a bear, but once it’s done, it’s done. All in all, the SU-GX70 is a stunning performer. And aside from its disappointing headphone output, I feel like most of its very minor problems can (and likely will) be sorted out in future firmware and/or app updates.
. . . Dennis Burger
Note: for the full suite of measurements from the SoundStage! Audio-Electronics Lab, click this link.
- Speakers: Paradigm Studio 100 v.5.
- Headphones: Audeze LCD-2, Sony MDR-7506, RØDE NTH-100.
- Speaker-level connections: Elac Sensible speaker cables.
- Interconnects: Monoprice Monolith #33464 USB Type-A to USB Type-B cable.
- Sources: Maingear Vybe PC, iPhone 12 Pro Max.
- Power protection: SurgeX XR115 surge eliminator / power conditioner.
Technics Grand Class SU-GX70 Streaming Stereo Receiver
Warranty: Three years, parts and labor.
Panasonic Corporation of North America
Two Riverfront Plaza
Newark, NJ 07102-5490
Phone: (201) 348-7000