Longdog Audio VDT1 PCM and DSD DAC is coming for a review soon at the Mono & Stereo. More upon the arrival, but here are few technical details:
S-PDif inputs:
Galvanic isolation with high performance pulse transformers.
RCA connectors with 75 ohm impedance.
110 Ohm AES XLR inputs available on request.
Supported speeds from 16bit/44.1k to 24bit/192k
SPDiff Receiver supplied by three separate ultra low noise voltage regulators.
USB Input:
Powered from Host computer, Galvanic isolation between Host PC and DAC, prevents noise from the host computer being coupled into the DAC.
USB Audio class 2.0 interface.
Driver free on Linux and OS X host systems.
Simple driver installation on windows.
Speeds from 16bit/44.1k to 24bit/192k (32bit accepted).
DSD over USB supported, 64bit DSD, automatic switching between
AK4396 DAC selected for best subjective sound when used in balanced out mode.
DAC powered by two ultra low noise voltage regulators. I2S and DSD input isolated from receiver to avoid noise transfer between stages.
Analog output from DAC taken directly to output buffer, no op-amps, capacitors or additional solid state devices in the signal path once it has left the DAC chip.
Analog stage:
Fully balanced valve output stage using 5687 dual triodes, and custom Sowter output transformers, with nickel cores and balanced winding patterns. Use of balanced design ensures distortion levels equal to solid state output stages, but with the sonic qualities that only valves can deliver.
All resistors in signal path are high quality Takman carbon film types.
Output via high quality RCA sockets, fully balanced XLR output available on request.
Output signal level 2.18v RMS full scale (single ended).
Power Supply:
Digital board has 4 stages of pre regulation using low noise regulators, feeding 9 individual ultra low noise regulators mounted next to the driven device. Custom board design providing isolated ground paths between stages to reduce noise induced jitter to a minimum. High quality parts used throughout digital stage to ensure optimum performance.
Analog board contains three regulated power supplies, one for the digital board main supply, one for the output stage valve heater supply, and a valve regulated high voltage supply using high voltage mosfet and EF86 pentode design. Low noise HT supply ensures ultra low analog noise floor.
Custom UK wound toroid transformer, with oversized core, shield and hum band, supplies power to the unit.