On paper that should all work together. The RCA outputs on the Ares II are 625 ohms and 2Vrms. The input impedance of the Simaudio 240i is 22,100 ohms with an input sensitivity of 370mV to 3V RMS. On paper that should work. The DAC shouldn't be overloading the input to the Simaudio and the impedance ratio should be OK. On specs I don't see what could be obviously wrong to cause what you're hearing. I don't own a Denafrips DAC. So can't experiment to help diagnose your problem. Hopefully you can figure out what's going on. Frustrating to have audible distortions like that and not know why, when on paper it should work.