Maybe I missed it in the above discussions, but may I ask are both the streamer and CD player run into your MF DAC? If so, what outputs from each into what DAC inputs? And then, what cables are you using? Please correct me if I am wrong, but the MF6si only has an USB digital input? I have an Emotiva ERC-4 CD player; it has balanced outs, so that is what you should be using into the integrated amp. If that is the case, then you can try something without spending more money on a DAC. Your ERC-4 is also a DAC. The Emotiva ERC-4 features two dedicated digital inputs, allowing it to function as a standalone DAC for external sources. It includes one Coaxial (S/PDIF) and one Optical (Toslink) input, both supporting stereo PCM audio up to 24-bit/192kHz. The unit does not feature a USB input. So you could try to route you digital output from your streamer into the Emotiva digital inputs (preferably S/PDIF Coax) and then into your balance analog input on the 6si, thus bypassing it's DAC. Then, if that doesn't improve the sound you should pursue buying an outboard DAC of your choosing. Good luck!