Wisdom in mind,   enthusiasm at heart.

Even though the PCM1704 PDF declare the PCM1704 support up to 96KHz / 24bit, highest word clock input is 768KHz.
In fact the PCM1704UK can support 192KHz / 24bit at 8X oversampling (USB or I2S model), the word clock input is 1.536MHz , as high as ESS9018.

Reference-10.32（USB applied USB-32）
Discrete  DAC + Headphone amplifier / Preamplifier

Built in DSP-1 data processor
32bit / 384K Asynchronous Transfer  USB-32 Chip
Built in 4 Pieces Hi-grade PCM1704UK Chips
OCC wires and TCXO built in
　

The unit applied analog input short design :
          The unit  had design the analog idle input short circuit (  In 6 to In 8) for avoid the disturb between different sources.
         This design also applied in a lot high end brand devices.
          The working theory :  Without the idle input short circuit ,if the input 7 and input 8 had connect two extra DACs,  while users select the either input 7 and input 8 , the another input signal will fire through the circuits and mix  into the using signal, even though this signal is  weak  but still can degrade on the sound quality.
          With the idle input short circuit function : if user select either the input 7 and input 8, the another input signal will short circuit then no any signal fire through circuits , can keep the sound quality had not degrade.

How to choose the Debug switch on rear :
Before 3th. March 2015 :
         Select  the "Debug" switch on rear to setting with / without memory function .
Since 3th. March 2015:
        Select the "Debug" switch on rear to setting the RCA ,XLR and ACSS output as preamp with volume control or DAC with fixed output .
        If setting to with volume control mode, the HP/PRE select to " P", the volume can control and with the digital number display .
       If setting to DAC with fixed output mode, the HP / PRE select to " P", the volume can't control, and the volume display " - - " .
        Please note : The Debug switch must change while power off .
        If your external amp had not volume control, please ensure the unit had setting to preamp with volume control mode before connect to the amp .

DSP-1 Jumpers setting