This is the ”reference” DAC in my audio system. It’s based on Twist Peal Audio (http://www.twistedpearaudio.com/landing.aspx ) Buffalo III SE board and consist in my implementation for best use this module. The heart of Buffalo III board is the ES 9018 ESS Sabre32 Reference DAC chip, that , whit its stunning performance is probably the best DAC actually available. It can handle 32 bit PCM data via I2S input as well as DSD or SPDIF data with DNR of 135dB and THD+N of -120dB.
To obtain a USB port and connect a personal computer as player for high-resolution files I use the Amanero Combo 384 module (http://amanero.com/). Amanero Combo 384 module support a sample rate of 44.1Khz 48Khz 88.2Khz 96Khz 176.4Khz 192Khz 352.8Khz 384Khz with output format I2S 32bit or DSD64, DSD128, on Windows DSD256,DSD512 too.
The Buffalo III SE board need a power supply of 5,25 V@440 mA. I tested various type of power supply and in particular it’s “sound characteristics” and at last I adopted a low impedance mosfet ( IRFP9240 ) shunt regulator. The 2,2Ω/7W resistor set the total current through mosfet M1: 680mA. Part of these, 440mA flows into the load ( Buffalo III ) while the remainder 240 mA flows through shunt device M2. Greater shunt current gives lower impedance ( better performance ) but consume more power ( large heatsink, big power transformer…. ). The bridge rectifiers are 1N5822 Schottky diode , LED diodes are green type, FET 2SK170, NPN transistor any general purpose ( 500mW ) device. 200Ω trimmer set the 5,25 V output voltage. CMC is a Common Mode Choke 100mH, 1A.
The Amanero board takes the 5V power supply voltage from USB port but I don’t like this solution and I have therefore foreseen an additional 5V power supply based on a linear regulator LM7805. On Amanero board remove L1 SMD coil and connect the +5V as the follow schema. The negative wire can be soldered on the USB metal case ( Ground ). The power transformer has two 9 V separate secondary coils @ 1 A.
The Buffalo III need an I/V stage buffer to match the differential current output from ES 9018 DAC. The most important feature of this DAC is the adopted two Triad HS-56V audio transformers to match the output signals. I tried both the configuration 600:600 Ω or 150 :600 Ω connected directly in the +, – pin out on the Buffalo board. No DC current flow in primary side due the equal DC voltage on the +, – DAC sides. Usually a I/V low value resistor is put on transformer primary side but after various listening test I connect a 10KΩ on secondary side. This value can be reduced to suit your taste.