This is my first PCM63 DAC. It uses CS8414, DF1704 and PCM63P-k x 2 pcs. The IV is resistor with 6922 SRPP tube output stage design. Overall the sound is smooth but it lacks of details. It is more or less the problem of SRPP and output drive is not good enough for most transistor preamp due to high output impedance. Thus it will also be sensitivity to signal cable used.
First modification is to use D1 mosfet IV, the result is improved on clarity and details.
Second modification is to use Jfet IV (K170BL). Later the IV is upgrade to K369BL in Jan, 2010.
Third modification is to add super low noise regulator.
Fourth modification is to add a power transformer and also two output audio couple transformer for balance mode.
