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Audio Research GSi75 integrated amplifier

Audio Research GSi75 integrated amplifier

If I were writing the recent history of hi-fi, one thing would dominate the tale – the rise of the ‘one box solution’. Although the market for discrete components in the audio chain is still strong, what was once dismissed as a ‘Jack of all trades, master of none’ is now highly prized as a practical way of getting the best of everything in one convenient package. The GSi75 by Audio Research didn’t invent this market, but it seems to have perfected it!

The new G-Series from Audio Research currently comprises a preamplifier, a power amplifier, and most recently the GSi75 integrated model. As the name suggests, the integrated is a 75W design, using the KT150s first used in the GS150 power amp and now featuring throughout Audio Research’s lines.

, Audio Research GSi75 integrated amplifier

In addition to being a good quality integrated amplifier, the Audio Research GSi75 sports a very fine phono stage, an outstanding upsampling DAC, and even a very high performance headphone amp. Unless you are desperate for balanced connections, or have a burning desire to stream from an amp, you are going to struggle to find an excuse not to look at the GSi75 as a one-stop audiophile shop.

The options the GSi75 provides are almost not the headline topic for the G-Series, though. Named after that well-known Audio Research enthusiast and son of Minnesota, the Renaissance Italian astronomer Galileo Galilei, the G-Series changes to the product design are every bit as radical; a clever and truly multinational operation to refresh Audio Research’s long-standing design cues without sacrificing all the brand stands for.

, Audio Research GSi75 integrated amplifier

The result is a taller, cleaner looking amplifier, without the front panel handles, and a design that harks right back to some of Audio Research’s earliest models, yet doesn’t look so retro it fails to appear fresh and new. The mark of good product design is similar to that of a really good song; as soon as you encounter it, you think it’s something you knew of for years, and the GSi75 nails that perfectly. This is the World Of McIntosh (née Fine Sounds) Group’s special sauce – few other big names in the high-end have access to an internationally respected Italian product design team. In truth, I was a little apprehensive at how the G-Series would have been received by Audio Research’s faithful following, but the response has been so welcoming that the design has ended up influencing core products like the new Reference 6 preamplifier.

It’s easy to get carried away with this and fill pages in the way Ian Fleming mastered (he could weave a page and a half about the patina of a Ronson lighter into the text without ever making it seem like ‘filler’) but the physicality of the GSi75 is not something to be sniffed at. It’s a large, sophisticated integrated amplifier for the modern music lover: it does everything you could think of, does it all well, and exudes a sense of absolute class in the process. It’s a tube amp for people who like the sound and the idea of tube amps, but don’t like all the fuss and bother they sometimes cause. Insert, bias, play… it’s all made extremely simple. Perhaps this is indicative of the influence of the new boss at ARC, Mike Tsecouras. Tsecouras comes from a Texas Instruments background, and TI isn’t the kind of brand that allows something less than fully professional out the door. The GSi75 has that kind of professionalism, and as a result makes a lot of traditional high-end audio look a bit, well, shoddy by comparison. This isn’t one of those “oh well, you know Barry… he’s a genius, but you have to turn his amplifier on with a long wooden stick because it might electrocute you” kind of products. This is designed to compete in a modern consumer electronics environment, where things are well made and competently designed. That we even have to say that about the GSi75 highlights just how bad things have got in the industry – all our products should be built to this standard, now. Not just a handful. Nevertheless, Audio Research deserves kudos, for raising the collective game in high-end audio, especially tube high-end. Other brands (and you know who you are), take note.


A lot of this comes down to the navigable menu system accessed from the front panel. This allows the basic operation to be ‘granny’ simple (as in, it should be easy enough to be used by the Industry Standard Saintly Old Grandmother, who only exists in fairy tales now, and not the more modern net-savvy Silver Surfer Granny, who knows more about TCP/IP than the average Cisco engineer). But it also allows the GSi75 to be configured very precisely, controlling startup volume level, standby switch off time, use with a home theatre system, and more. There is even a tube life clock, so you can tell just how long before you need to replace a set of tubes. These functions are not required for day-to-day use, and are therefore removed to the on-screen menu. Note, however, that some of the functions of the amp are removed to the remote control, and at first seem like they might be better served by being moved to the menus. Adjusting loading, for example, ends up an on-the-fly tonal adjustment rather than a once a cartridge event, and handset access is then vital.

, Audio Research GSi75 integrated amplifier

You do need to access some of the controls of the DAC, though, and these are neatly placed along the far side of the amp. Aside from racking through the inputs, the DAC – which upsamples to 24-bit, 352.8/384kHz (depending on original sampling frequency) and supports DoP DSD replay – also includes ‘fast’ and ‘slow’ digital filters; these do help cope with the vagaries of modern (and especially online) digital sources. The days of manicured audio files are being replaced by technology that can be used to make the OK sound pretty good, and the good sound great, and that is what the GSi75’s DAC section does so well.

In fact, the on-board DAC is so damn good, if you disabled all the other sections of the amplifier and merely created a £16,000 DAC with this kind of performance, I don’t think anyone would be too upset at the package. OK, they might question the lack of AES/EBU, Ethernet, and a wider range of inputs, but from a sheer sound quality standpoint, it would not be that far out of place as a standalone DAC in its own right. There’s a relatively heavy statement that drops out of that; to date, this is the best digital converter that has ever gone into any Audio Research device, including its Reference DAC and CD players. It doesn’t render those devices entirely obsolete, in part because the standalone players and DACs bring their own functionality and flexibility to the mix. But in outright sound quality terms, the DAC inside the GSi75 is the best digital ARC has yet delivered.

The phono stage would also work its magic as a standalone, although at the price also you’d be wanting some extra functionality, such as a wealth of EQ curves. In fairness, unlike the DAC section, most good standalone phono stages have the better of the one on the GSi75 if you compare them side-by-side, but if you don’t make that comparison and listen to the sound of records played through the GSi75, that sound is so immensely satisfying and musically absorbing, such comparisons will quickly fade from interest.

, Audio Research GSi75 integrated amplifier

And in a way, ‘musically absorbing’ is the GSi75’s core strength. You just sit and listen and enjoy. Then you repeat the exercise. That’s it! You don’t feel the need to analyse the nature of sound, or over-analyse the music being played. It’s all there, with the kind of clear, yet warm and inviting sound that reminds you in winter of beach parties in the Tropics. It’s a mildly forward presentation compared to, say, the conrad-johnson amp tested in this issue, but not so forward it sounds aggressively so, and I’d argue this is one of the most ‘poised’ amps in the market right now as a result.

Of course, the GSi75 ticks all the right boxes. It has a large bolus of sound surrounding the loudspeakers, and in that sound is good stereo separation and image depth. But the key aspect you pick up from the imaging is the solidity of sound, something you might normally expect from amps more powerful – and usually more separated into different boxes – than the GSi75. Put on a piece of music with a vocalist front and centre – Ryan Adams singing ‘New York, New York’ from his 2001 Gold album [Lost Highway] for example – and you are met with a vocalist standing out from the rest of the musicians, in their own physical space. Swap Adams for Janis Joplin and you feel like you are sitting in front of a force of nature. And this is with a pair of Wilson Duette II’s; while not the most difficult speakers to drive, they are at their best when driven hard and loud.

The Audio Research has that intrinsically right, proper, and fun confluence of deceptive power and authority, exceptional detail, and a fine ability to pick out a bass line and boogie with it. If that sounds a little old fashioned, it’s because you can’t help play something old fashioned through the GSi75: I pumped out ‘La Grange’ by ZZ Top [Tres Hombres, Warner] at ‘healthy’ levels and played air guitar, air bass, air drums, even air beard through the course of the track. When things sound this fun and this real, how can you resist?

Yet, this is the kind of amp that can reveal subtlety and nuance when asked. It’s not just a head-banger; I played Górecki’s Symphony No 3 [Zinman, Elektra-Nonesuch] and the combination of Dawn Upshaw’s soprano soaring above the London Sinfonietta’s respectful playing made for a genuinely moving experience, unconstrained by the electronics.

Perhaps the most significant aspect of the amplifier is its coherence. Not just in the way it retains the same timbral properties across the frequency range, but in the way every aspect of the amp seems designed as a cohesive whole. The DAC is great, and is tonally from the same stock as the phono stage and the line inputs. Yes, the source components will dictate the full extent of the performance from each input, but the overall texture of the sound is very much Audio Research and incredibly coherent. Nothing sounds out of place here, both in terms of end result and switching from source to source. Once you factor in the fact you actually want to hear more from each source, you know you are on to a winner.


Even that headphone amp is no simple afterthought, and given the antipathy most conventional audio brands have toward the headphone world, we might expect something a little so-so here. In fact, the headphone amp is powerful, detailed, and dynamic. It’s also got that unique ‘clean, yet warm’ sound of ARC, and is not afraid to apply that to all bar the most recalcitrant of headphones.

, Audio Research GSi75 integrated amplifier

With a very few exceptions, I’m struggling to think what you might miss by buying the GSi75. Extra boxes perhaps. OK, so there’s no built in wireless connectivity, and 75W – no matter how good sounding – will never drive difficult loudspeakers to high levels in big rooms, but with those caveats in place, there’s nothing wanting from the GSi75 at all. That might sound trite, but when you think just how much more you need to spend and how many more boxes you need in the room to improve on the GSi75 in fundamental terms, you begin to see why this is something really special. Hook this to a good turntable, a computer full of tunes, a good set of headphones, and an equally good set of loudspeakers, and you could be set for life. In the never sated world of high-end, that has to be about the highest recommendation one can possibly make!

Technical Specifications

Type: Integrated tube amplifier

Valve complement: 2× 6H30 drivers, 4× KT150 power tubes

Analogue inputs: 3× RCA stereo

Phono stage: MM/MC, adjustable input voltage and impedance

Digital inputs: S/PDIF digital (coax RCA and Toslink), USB (driver required for Windows PC)

Sample rates supported: 44.1kHz to 192kHz, S/PDIF and USB 2.0 HS, DSD USB 2.0 HS

Input sensitivity: 0.55V RMS rated output. (32.5dB gain into 8 ohms.)

Input impedance: 52.5kΩ

Maximum input: 10 volts RMS

Power Output: 75 watts per channel continuous from 20Hz to 20kHz.

Frequency Response: 1Hz-70kHz (–-3dB, 1 watt)

THD+N: Typically 1.5% at 75 watts, .05% at 1 watt (1kHz)

Power Bandwidth: 12Hz to 70kHz (–3dB)

Overall negative feedback: 4dB

Output polartity: non-inverting

Output taps: 4Ω, 8Ω

Dimensions (W×H×D): 48.3×26.3×51.8cm

Weight: 25kg

Price: £16,000

Manufactured by: Audio Research Corporation

URL: www.audioresearch.com

Distributed by: Absolute Sounds

URL: www.absolutesounds.com

Tel: +44(0)208 971 3909


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