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• D/A Converter or Processor
The Questyle Audio CAS192D Digital-to-Analog Converter
Unlike other DACs that claim DSD support, yet in actuality provide DoP (DSD over PCM), the Questyle Audio CAS192D accepts the DSD bit-stream directly from your computer, bypassing your computer’s audio processing and digital volume control as well as the Questyle Audio CAS192D’s digital filters, to provide True DSD, the way it was meant to be heard. This, without requiring expensive difficult to install proprietary connectors, or as is the case with DoP breaking up the bit-stream into 16bit packets and compressing them into a PCM data-stream and then uncompressing them at the other end, buffering them, then reassembling the bit-stream so that it may be sent to the DAC as DSD. All of which requires an extreme amount of processing at both the computer end and the DAC end to perform in real time (which invariably leads to latency, data loss, etc), not to mention a 33% increase in bandwidth requirements for the USB ports and cabling.
IIR Digital Filter
Currently the majority of DACs use FIR (finite impulse response) digital filters, but research and testing has shown that our ears are very sensitive to the pre-ring that FIR digital filters add to the impulse wave, making the music sound incoherent and unnatural. The Questyle Audio CAS192D offers the more advanced IIR digital filter, which completely eliminates the pre-ring from the impulse wave producing a more natural sound.
USB Input Supports True DSD and PCM 192kHz/24bit, 3X Clock Asynchronous Transmission Structure
During every second of music, there are hundreds of thousands of time operations. Any micro errors will distort the sound. In the Questyle Audio CAS192D, a 3X clock USB asynchronous transmission structure ensures a more accurate operation. To obtain first class sound performance, three correspondence level clocks (custom made in Japan), individually control multiples of 44.1kHz, multiples of 48kHz and USB signal transmission, dedicated for USB asynchronous transmission, reduceing Jitter to undetectable levels. A three-clock integrated circuit with FIFO asynchronous architecture and three voltage-stabilized power stages ensure accurate sound.
Dual Clock Integral Upsampling
When upsampling, 44.1kHz does not divide evenly into 192kHz, causing timing errors. To avoid this, CAS192D uses two clocks, with extremely low phase noise, thus the processor automatically identifies the sample rate and upsamples integrally. If the input data is 44.1kHz, it will be multiplied by 4 to 176.4kHz; if the input data is 48k, it will be multiplied by 4 to 192k, which avoids those negative effects. The upsampling is ASRC to avoid Jitter. On the front panel of the Questyle Audio CAS192D, there is an UPSAMPLING button to allow the user to choose whether to upsample or decode at the original sample rate (the current state of operation is displayed on the screen).
Specific Power Supply
The power supply section of the Questyle Audio CAS192D is second to none. A customized Plitron toroidal transformer, Schottky rectifier, 22pcs Nichicon 2200uF FG capacitors, 22 groups of individual power regulators, all ensure each section a stable and purified power. The DAC chipset uses 4 levels of digital filter and power regulation.
The Questyle Audio CAS192D aluminum chassis is produced by Foxconn using precise CNC tooling machines. The upper cover and bottom chassis “mutual bit” structural design, provide the Questyle Audio CAS192D with stable heat, excellent control of sympathetic vibration and excellent shielding of RFI/EMI radiation.
The sound of WM8741 can be described as classic "English"-style, delivering a soft and exquisite sound. Due to Questyle's high requirements for D/A design, LPF is discarded (per Wolfson ’s suggestion) in the Questyle developed analog output circuit for the WM8741, receiving official praise from Wolfson.