1-bit, multiple possibilities. After the debut of Head-Fi's first discrete 1-bit, all-to-DSD, music player in N7, Cayin Audio have miniaturised the technology further in RU7.
This latest novel 4.4mm USB DAC/amp from innovators Cayin therefore promises to upsize your enjoyment of music with the same decoding topology that saw N7 greeted with aplomb.
Built of 128 individual resistors, RU7 converts all your normal PCM playback – via CD rips, Hi-Res downloads and Spotify, Tidal or Apple Music streaming – into DSD before decoding to analog.
Its size is proof that no task is too big for Cayin. Outputting in 4.4mm, RU7 is Cayin's perfect complement to the PCM, R2R, RU6. Headfonics says RU7 is "the best of the lot". Headfonia elected this mini DSD masterpiece to its Recommended Buys list. eCoustics add "it's the best dongle DAC we’ve tried yet".
"RU7 continues the company’s hot streak of breaking new ground in DAC design ... 1-bit DAC in the RU7 is even more impressive than the R2R DAC [in RU6]" says The Headphone List. To Twister6 and ichos-reviews, RU7 even challenges DAPs.
Bringing up to 400 milliwatts power to bear, the goodness of an all-to-DSD approach to decoding can be heard with all manner of portable Head-Fi. [See Product Desc. For More]
All audio formats are passed as DSD through RU7's precise 1-bit decode. Cayin returns to Sony's Scarlet Book SACD revolution of the 1990s and elevates that conversion philosophy with modern mobile dongle hardware.
RU7's highlight is its 1-bit decoder, converting all PCM files to quad-rate DSD first via DSP logic, while letting native DSD material flow on to the 128 discrete resistors in its DAC – in actuality a simple analog low-pass filter.
There's zero error at the point of conversion in a 1-bit DAC. There, Cayin relies on Pulse-Density Modulation (PDM)'s total accuracy, and sheer ease of decoding.
The pitch for DSD's 1-bit conversion is digital at its simplest and closest point to analog – level represented only either as a 1 or a 0, switching on or off. To achieve analog, the bitstream is simply low-pass filtered.
Cayin's all-to-DSD discrete DAC is accurate ... and also elegant, breakthrough and historic in personal audio. It draws inspiration from the illustrious halls of Hi-Fi, where each EMM Labs, Nagra Audio, Playback Designs, PS Audio and of course, N7's, 1-bit DAC release has been greeted with accolades and fanfare.
RU7's discrete proprietary tech immediately differentiates itself from commercial DAC chips, where IC packages are often too small to perform an ideal 1-bit conversion. RU7 also avoids the errors of dynamic element matching inherent to 2-7 bit delta-sigma decoders.
The decoded analog goes through Cayin's specially designed resistor-based analog volume control for perfect channel matching at any level – facilitating that very special 1-bit discrete DSD decode and importantly preserving your music's true dynamic range resolution.
A series resistor operates with shunts as voltage dividers in tandem with relays, to maintain near-perfect resolution of your music and a signal-to-noise ratio of over 110 dB. A totally novel volume solution has made this feat possible on a USB-powered dongle DAC.
Cayin differentiates RU7 from RU6 in offering the former a line-out option whereby the volume control is bypassed for a fixed voltage out, perfect for listening into motor stereo systems as well as handy and portable personal speakers.
Meanwhile, RU7's 400mW output power is doubled compared to RU6's, such that this DSD DAC is capable of transferring all its forward-thinking fidelity into your prized transducers. Never fear for leaving your reference gear behind for Cayin's latest and greatest every-day carry.
There ends the list of exploits worthy of celebrating Cayin's 30th anniversary in arguably more ambitious a way than even N7 offered. Check out the rest of Cayin's gear here, or view our other USB dongle DACs here.
