Evolve or go extinct: RS6 brings portable R2R into a new future

We’ve reached the tipping point. A decade of digital audio in Head-Fi prepared us for this moment. We’ve heard of the Wolfson sound, ESS sound and AKM sound, and heard them too. A conversation that distracts from the music? It's nevertheless digital reproduction – every converter present will always add and subtract something from the music.

We digress. The Wolfson sound, ESS sound, and AKM sound were all formative to our understanding, learning to describe what we were hearing and experiencing, for the ears of others. Retain that progress, though, as we begin learning to describe portable R2R. 

That’s because R2R in music players looks here to stay. HiBy Music’s RS6 is evidence it’s here to thrive, too. Made of a ladder of individual resistors instead of a mass-produced, DAC integrated chip, the byword for RS6 more than ever is it’s a proprietary DAC designed from the ground up, named DARWIN. It’s a natural evolution.

BUY NOW HiBy Music RS6

Nothing exactly like it, before or after, HiBy passed RS6 for release. What’s R2R to sound like – there’s nothing nailed on because discrete R2R sounds exactly like what HiBy wants theirs to sound like. R2R can vary wildly in sonic results. No two discrete architectures play exactly alike.

Customisation by HiBy, however, took place for more than just tuning. It extended to RS6’s capabilities. We’ve banged on about the non-oversampling (NOS) PCM conversion in RS6’s R2R ladder. 

READ ALSO Step up RS6 with palm powerhouse C9

To convert at the original PCM sample rate without re-sampling or oversampling (the latter’s a built-in secondary option) is doubly impressive because of the double accuracy necessary in individual resistor parts, operating without a digital filter.

Jeff Zhu of Holo Audio, with a mirror ladder, and Cees Ruijtenberg, who separated PCM’s most significant bits from the least significant bits, are two of the last decade’s digital audio luminaries. Their original work imparted ultra-precise, ultra-linear, NOS decoding in their R2R products. But said products were full-size Hi-Fi mounted in racks, with accompanying price tags.

It is on these shoulders that HiBy shrank a discrete NOS converter into a palm-sized music player and built a linearity compensation circuit to ensure accuracy of the decode and respectable noise and distortion performance – without the crutch of an oversampling process.

NOS is the harder way. Whether it’s the better way, your ears will tell you. While we’re explaining it, HiBy did R2R the hardest way (miniaturising everything) to remove oversampling digital audio filters – because oversampling digital filters are audible. 

We’d typically want our digital filters to sound as much like music, as music. But nothing sounds like music as much as original sample rate PCM files. Which leads the conversation to DSD.

Music is music. SACD and DSD is music. Whatever position you occupy about the business aspect that brought this five-per-cent format to market, some of our favourite music is in DSD. Which makes playing this back the right way of utmost importance, too.

DSD’s point is that it’s a 1-bit digital format; the closest point digital is to analog. DSD – or scientifically, PDM – is a fundamentally different digital audio format to PCM. It’s something RS6 recognises: and therefore converts DSD via an entirely dedicated 1-bit circuit, separate from PCM. 

We love this image – it tells us so much with so little. Follow the trail. DSD’s pitch as a 1-bit digital format is that it’s magnificently easy to decode. Just low-pass filter it. Analog comes out, in one stroke. A breeze, compared to the extra steps – and extra room for error – it takes for PCM.

Certainly, HiBy’s schematic above highlights DSD’s simplicity. And if you’ve a DSD file, you’ll want to hear it native with a total lack of pre-conversion to PCM, via RS6. The reason: no digital t̶a̶m̶p̶e̶r̶i̶n̶g̶ filtering happens to the original DSD.

VIEW ALSO All of HiBy's other DAPs here

As 1-bit, DSD is digital’s closest point to analog, making the transition from digital far less convoluted, and error-free – so long as it stays 1-bit. German champs T+A elektroakustik prominently build separate PCM and DSD hardware decoding paths. While EMM Labs, Playback Designs and PS Audio go one further: convert everything to DSD.

Those merits are for discussion another day. It suffices now to say that great DSD conversion and playback has scientific research behind the backing it’s better. HiBy doesn’t swing in favour of either format. If it’s PCM or DSD you do, RS6 will do it best.

Since RS6's hardware integrity is integral, it wouldn't be any less apt for its bit-perfect Android 9 software to be up to par. Crossroads commonly occur in audio. Having new Hi-Res Lossless ALAC from Apple Music decoded to full resolution, with an R2R touch, has us clutching our streaming accounts even closer.

DARWIN is a different breed, clearly. And D to the A that ignites our fire to listen to more music elevates it in our consciousness. So HiBy comes at us, the tipping point.

Whether your preferences of DAPs swung Wolfson, ESS or AKM in the infancy of yesteryear, the time has come to step up the evolutionary chain and acclimatise to the sound of DARWIN; rich, resolving, R2R. It's here with us to stay.