Audio GD R28 NOS balanced preamp and hp amp, R2R DAC

This is an Audio GD R28 DAC, preamp and headphone amplifier. It sounds amazing, but I ended up going with another DAC, so I'm selling this. It's in close to perfect cosmetic condition, but I'm rating 8 as I'm the second owner.

This comes with a power cord, the original box, and a remote control. It also comes with some extra parts, like pin jumpers and a device for flashing the firmware. Unfortunately Audio GD doesn't provide a paper manual with this and it takes some fiddling to understand it. There's an online manual but the English is difficult to understand. Nonetheless, I figured out all the functions.

Here's some information from the manufacturer:

The R28 NOS is a Fully Balanced solid state preamp with 9.5 watts per channel headphone amp and a resistor ladder DAC. We continue to be shocked at this level of sonic performance along with this feature set at this cost. Comparable products sell for $3000.00-$4000.00 range from the competition.The preamp or DAC alone is worth he price of the entire product. DAC’s of this quality typically sell for over $3000.00.

The R28 features 8 fully discrete R2R DAC modules to combine into a real balanced push/pull digital decoder as well as 4 fully discrete real balanced DSD native decoders. The DAC uses two 90/98 MHz Accusilicon 318B femto clocks to provide ultra low jitter.

The Amanero USB input supports 32bit / PCM384K PCM and up to DSD 512 asynchronous transfer. Clocking is done by a custom programmed FPGA. The whole digital circuit is built around one custom programmed FPGA and 5 CPLD programmable chip sets to separate the different circuits for avoid any interference in the data process in parallel mode.

The R28 headphone amp has two gain modes, 12DB in the low gain position to drive higher efficiency headphones at over 95dB sensitivity, and 22DB on high gain with the full 9.5 watts to drive any lower efficiency phones such as the HifiMan HE6 at 85dB efficiency.

The custom internal software that runs the unit is upgradable to improve sound quality in the future. All digital process mode settings are accessible by buttons on the front.