Arcam rPAC review

As ever more of us listen to our music collections from our PCs, we’re often at the mercy of dodgy on-board audio devices. It’s easy to find a sound card for less than £30 that’ll improve on most integrated audio, but cheap audio hardware often sounds just that.

This is where DACs come in. While sound cards include Digital to Analogue Converter (DAC) chips, they’re also kitted out with Analogue to Digital Converters (ADCs) for audio input, as might be required to record an audio file or chat on a microphone. Many – but not all – also have a dedicated audio processor, while cheaper models will have a single codec (short for coder-decoder) chip which integrates both DAC and ADC, generally at the cost of some audio quality. The most popular dedicated audio processors are made by Creative and C-Media (the latter appear in rebranded form on Asus’s Xonar cards) and take the load off your PC when it comes handling features including MIDI processing, gaming audio effects, implementing virtual surround sound or converting stereo audio data into something which can be output by 5.1 surround sound speakers.

These features are all potentially useful to someone, but if all you want to do is listen to high-quality stereo sound and get the most from your music, there’s no point in paying for ADCs and dedicated audio processor chips when you could instead buy hardware with a really high-quality DAC. That’s where devices like Arcam’s rPAC come in.

The rPAC is a tough little metal box with a rubberised base that’ll easily sit on the desk next to your PC keyboard or laptop. Its weight means that it’s not prone to shifting or being dragged around by any cables you have connected to it. The rPAC connects to your PC via a USB port and has both a 3.5mm stereo headphone output at the front – this has a dedicated headphone amp stage and its own volume controls – and a pair of stereo phono ports at the back, so you can connect the DAC to your amplifier and speakers.

Inside, there’s a Texas Instruments (previously Burr-Brown) PCM5102 DAC, RF suppression to cut out interference from common sources such as laptops plugged into unshielded power supplies and an asynchronous USB chip, which maintains its own accurate clock to control the amount of data being passed through it, minimising the chance of (already rare) glitches in your sound.

We tested the rPAC with a pair of Behringer Truth studio monitors and Shure SH535 headphones, equipment that’s good enough to really show up both the flaws and qualities of the sound. The DAC has a maximum sample rate of 96kHz and a bit depth of up to 24-bit, but you’ll probably spend most of your time playing audio files recorded at 44.1kHz and 16-bit, the specification of the CD audio standard. The rPAC has a frequency response of 10Hz to 20,000Hz and a Signal-to-Noise Ratio (SNR – a measurement indicating how much more powerful the signal is than any background noise) of 106dB, while the dedicated headphone amp has an SNR of 98dB.

In terms of audio output quality, the rPAC’s nearest match among our reference kit is the production-oriented Propellerhead Balance, but the rPAC kicks out more volume and sounds a little brighter. Its sound quality is nothing short of stunning – flat, balanced and with a great sense of space and separation. We were particularly impressed by the reproduction of recordings with strong stereo separation.

All our musical test files, from a vintage recording of the LSO performing Beethoven’s 6th symphony to the loud, busy and intricate guitar work of melodic death metal, were reproduced in stunning detail. You can hear the slap of drum skins, fret noises from guitars and breath sounds from woodwind instruments as clearly as if you were in the same room with them.

Although this DAC sounds astonishingly good, particularly if you’ve got high-quality equipment to go with it, it’s definitely not for everyone. Most PC users will be entirely happy with a cheaper device that can also be used for surround sound entertainment or for recording from a microphone, whether it’s an internal sound card such as the Asus Xonar DX or an external device in the vein of the Creative Sound Blaster X-Fi 5.1 Pro.

The rPAC is entirely unashamed about what it is – this is a high-end USB audio processor for people who’re really into their music. We’re not keen on the term “audiophile”, but if anything qualifies as an audiophile sound card, then this does. Also, at £150, it costs less than many audiophile-branded sound cards and benefits from portability and fantastic audio reproduction. If you have high-end speakers (or fantastic headphones) and rip your music at the highest quality around, then the rPAC belongs on your desk.