Hi, I have Asus Xonar Essence STX as PC sound source with changed opamps BB2111 and realy like the sound. Next as source is Marantz CD5001 and do have a cable tv Cisco HD receiver with some nice music channels. Amp is Marantz PM7001 KI with Monitor Audio RX2 and sw REL T2. Which DAC would give noticeably better sound using spdif from all sources? DAC could be even diy form, got an advice to try one CS4398 diy kit. Thanks in advance.