Electronics Overview
PCM1793 DAC Chip
The PCM 179X series digital to analog converter family is everywhere in the high end audio market. The PCM1793 DAC is a mid level chip in this family, with up to a 24bit, 96 KHz sampling rate and a signal to noise ratio (SNR) of 113dB.
PCM1793 DAC Specification Sheet
PCM2704 USB Interface
The PCM2704 is actually a USB based DAC chip but it also supports a S/Pdif interface, so in this design it is basically being used a USB receiver chip. This chip gives the SF MKII DAC true Plug n� Play with no drivers but it limits USB to 16bit, 48 KHz.
LM4562NA Opamp
The famous LM4562NA, this opamp seem to be showing up everywhere these days in the desktop audio market place and for good reason as it offers excellent specifications.
The LM4562 is a fast opamp with a high slew rate of �20V/�s and an incredibly low THD+N of (0.00003%), so we can see why it is used in more and more modern designs. The opamp is in a socket so you can swap it out for other units if you wish. The LME49720HA, Dual LME49710HA, AD797, Dual LT1028, Dual OPA627 or some discrete might be an option here depending on your tastes.
A quick note: FSA used a milled opamp socket in this design which is considered a higher grade socket that stands up better to multiple opamp swap outs.
