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Audio Reviews
15,670 Reviews PC Advisor Recommended

ADL GT40 review

£395 inc VAT

Manufacturer: ADL

Our Rating: We rate this 4 out of 5

The ADL GT40 from Alpha Design Labs is a D-A convertor with a difference – it can also turn analogue audio into digital, serve as a turntable phono stage, and a headphone amp and even replace a pre-amplifier.

Breaking out the audio from your PC or laptop is generally a good idea. For laptops especially, there’s little option to upgrade the average-quality audio electronics on board; and tower PCs are a dying breed, with many popular PCs now appearing as all-in-one or small media-centre packages that simply can’t be upgraded with old-school soundcards.

The Alpha Design Labs GT40 can certainly take on digital-to-analogue conversion, connecting to PC by USB 2.0. But it has other particularly useful capabilities too.

Besides its digital-to-analogue convertor (DAC), specified to studio-spec 24-bit/96kHz operation, it also offers a 24/96 analogue-to-digital convertor (ADC) for taking older sound formats and turning them into digital audio.

Applications here include archiving vinyl records and cassette and reel tapes. Digitised audio is transmitted back to the PC over the same USB cable. And once captured to hard disk (with an audio editing program such as Audacity), these audio files can be repurposed for playing on an iPod or smartphone, burned to CD, or amassed on a NAS drive for streaming around the home.

In the case of vinyl recording, you don’t even have to worry about a turntable phono stage, as the ADL GT40 includes the requisite input – and one that accepts either popular moving-magnet (MM) pickup cartridges, or the more rarefied moving-coil (MC) type.

A full stereo system is not essential to monitor your labours, as the GT40 also includes a superb headphone stage with its own volume control.

If you do connect the ADL GT40 to your hi-fi, that knob acts as a master analogue gain control. Which means you could wire the unit direct to a stereo power amp, bypassing the extra stage of pre-amplifier. Audiophiles will have a lot of fun exploring the possibilities here.

Furutech heritage

Alpha Design Labs is a new brand with a long history. It’s a spin-off of Japanese audio cable specialist Furutech, respected for its high-grade speaker and interconnect wiring, along with associated high-end plugs and socketry.

Which explains the use of remarkably fine Teflon-dielectric RCA phono connectors on the rear panel – one pair each for audio input and output. Also here is a small slide switch to select between MM and MC sensitivities, or line-level input.

The whole construction of this diminuitive box is to a very high level, from the sockets to heavyweight alloy chassis to the smooth volume pot with its precision-milled knob.

Sound quality

Connected to an Apple Mac mini, we were able to set up the ADL GT40 to work at different resolutions, from 16-bit/44.1kHz (CD-audio level) up to 24-bit/96kHz operation.

For playback of CDs and CD rips, we stuck to the former resolution, to reduce the amount of real-time processing being undertaken in the PC. But for recording, we urge you to go straight to 24/96. It really is the best way to preserve most of the original analogue sound.

Using the ADC feature, and found this stage to be of generally very good quality. By selecting ‘Phono/Line’ with a fascia button, you can play through the unit and out of its outputs, without any need of a USB connection to computer.

When we did connect up the USB though, a low haze of digital hash was heard in the background, distinctly audible in the noise floor. It’s possible that different computers and hi-fi combinations will be less affected; but especially with the high-gain MC input selected, the disturbance could prove too much for high-quality archiving. Which is a shame, as the meaty sound of vinyl though this unit was very promising.

As a playback DAC, though, we had fewer problems. In fact, after some time running-in, this device really opened up to establish itself as a favourite in the system. Furutech makes no claims of asynchronous-mode USB transfer, but the essential sound of the ADL GT40 was well ahead of any legacy adaptive-mode USB audio device we’ve heard before.

There’s an unmissable solid and well-propelled drive to bass. Soundstaging is neat and quite tightly defined. Treble could be get slightly harder sounding at times, yet dulled at the very top, and never too abrasive. In comparison to super-fi DACs, the ADL GT40 could be said to lack some air and translucency.

Best of all, though, was the ADL GT40’s ability to make good sense of the music. It really put space between musicians, giving the music room to breath.

Perhaps there was some particular quality of good phase coherence, but we found it altogether quite natural and analogue in its presentation, simple as it sometimes was. Not unlike the Naim sound, it held our focus on the musical essentials.

The ADL GT40 is distributed in the UK by Sound Fowndations.

ADL GT40 Expert Verdict »

24-bit digital audio convertor
D-A and A-D conversion
USB 2.0 Type B connection
phono stage, 5mV moving-magnet with 48.5dB gain, and 400µV moving-coil with 62.5dB gain (both @ 1kHz)
manufacturer’s performance specs: 20Hz–20kHz frequency response (+0.5dB at 40Hz/-0.5dB 15kHz)
‘-90dB (A-wtd) S/N ratio’
1V rms line output level
80mW headphone power output
9V AC adaptor
150 x 111 x 57mm
  • Build Quality: We give this item 9 of 10 for build quality
  • Features: We give this item 8 of 10 for features
  • Value for Money: We give this item 8 of 10 for value for money
  • Overall: We give this item 8 of 10 overall

The GT40’s A-D conversion was marred a little in our setup, but results may vary in different systems. Full galvanic isolation between PC and hi-fi would help here, but considering the key features offered here at an affordable price, this stands out as a very well made audio convertor. For its main task of playback DAC, it’s a little marvel.

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