*SOLD*
Audio-GD R8 MK2 - FPGA controlled R2R PCM/DSD DAC.
SUPERB sonics. Excellent condition. Box and manual. $1,200 obo plus $50 shipping in 48 States. Paypal adds 3% unless you use F/F.
https://www.underwoodhifi.com/products/audio-gdDescription from the distributor's website:
At under $2,000 this is easily the DAC to beat. It clearly outperformed the PS Direct Stream that we compared it to.
R-8 MK2 features:
Fully balanced XLR, RCA and ACSS (CAST) connectivity
The R-8 MK2 upgrade started at the beginning of 2020, which was followed by a year of continuous audition, software and hardware fine-tuning. Using the latest discrete servo stabilized power supply, whose performance is comparable to batteries after more than a year of calibration and optimization each part of the circuit was refined and optimized.
The new MK2 DAC uses a new discrete servo stabilized power supply while the analog circuits are still powered by pure class-A power supply to achieve the best sound, as determined during many long listening tests.
The improvement is quite obvious compared to the previous generation.
1. Fully discrete parts are used in a truly balanced current transmission design. Four sets of fully discrete and independent DSD hardware decoders. Eight sets of fully discrete R-2R DAC modules are used to form a two-channel balanced push-pull decoder.
The R8 MK2 uses the newly designed discrete servo stabilized power supply to feed the DAC circuits. In the new DAC the noise level is now comparable to that of a battery, but without the dry and thin sound characteristics of it, and thus the product's operating temperature is significantly lower than that of the previous model. The analog circuit are still powered by a pure class-A regulated power supply for the best sonic results.
2. By listening to a turntable and studying its sound for a long time, Audio GD has successfully integrated an analog vinyl sound characteristic into the DAC. This tonal balance is optional and controlled through the front panel. This is a new feature.
3. Both the USB and HDMI inputs are equipped with opto isolators, and two sets of linear power supplies to separately supply power to the USB and HDMI modules before the isolators to prevent interference from signal sources. The USB input uses a two-way transmission isolator, which not only transmits IIS signals to the FPGA processor, but also receives the synchronous clock signal sent by the FPGA processor.
The USB interface itself is no longer equipped with clocks. The synchronous clock is applied to make the signal transmission more accurate and upgrade sound quality significantly over the older model. The HDMI module is now equipped with an independent isolator to improve the sound quality of the HDMI input.
4. The MK2 now has a display of the input signal sampling rate function.
5. The digital circuits of the whole DAC are comprised of 1 FPGA and 5 CPLDs (both programmable devices), which allow separating the different functional circuits and preventing interference. The FPGA operates using the parallel data processing mode. The parallel mode only needs one clock to transmit and process the 32-bit data of the left and right channels, which greatly improves the processing speed and is less affected by the stability of the clock.
6. Two superb Accusilicon Femto clocks provide synchronization for the whole unit, and they are applied to the playback of all data rates without PLL up-conversion. The clock management design of the new architecture makes the clock more stable, which brings a more transparent and detailed presentation.
7. DSD uses the built-in asynchronous clock to enhance timing, which obviously improves the clarity and dynamics of reproduction.
8. SPDIF supports DOP playback.
9. All digital mode settings can be changed on the front panel live.
10. A firmware upgrade port is on the rear panel so there is no need to open the cover to upgrade the firmware.
