Klein DAC III Design
This is a very basic USB only DAC based on a minimalistic high quality Jensen transformer output stage. Its design is inspired from a scaled down version of the Fein/Gross DAC's.
USB input is via a Amanero Combo 384 board which is powered with a dedicated ultra low noise PSU so it does not require USB input power to operate.
The DAC chip is a premium AKM AK4495EQ. I actually prefer the sound of this chip over the more commonly used AK4490EQ (Klein I & II) It has four selectable digital filters which are configured via two pcb jumpers. The reason for the pcb jumper selection rather than switches is twofold. 1. There was physically not enough room for filter switches on the rear panel due to XLR sockets. 2. Most users preferred one particular filter so I have just pre set the jumpers to that.
Output is balanced (XLR) or unbalanced (RCA) selectable via a switch & is approximately 2.5v RMS. File format is PCM only up to 32 bit 384K. The DAC is powered by a external 9v 2A transformer. Inside there are ten independent regulated PSU's. Rectifiers are high spec low switching noise Schottky's. Main filter caps are Elna Silmic II's. All the other caps are Panasonic FM's or super low ESR Vishay SMT polymers. The AK4495EQ has dual massive 22000 uf VREF filer caps which give a very low distortion & extended bottom end.
The net result of all this is a superb sounding basic PCM USB only DAC at a great entry level price.