Hello Ykar, could you please tell us a bit more about the power amplifier you are using? I have just ordered the Topping A70pro and I'm planning to use it primarily as a preamp to my Boxem Arthur 4215/E2 Purifi Eigentakt power amplifier.
I expect very little difference between D70 PRO SABRE and D70 PRO OCTO. Considering the slightly higher THD+N of the Octo, it will also have a slightly lower SINAD. Maybe somewhere between D70 PRO and E70. But we won't hear the difference anyway.
Hi Loysius, I see you placed your 803d4s very near to the front wall. That might explain the peak at 40Hz without room correction. Did you consider placing them farther from the front wall? That will change the frequency response without room correction and might improve imaging too.
One thing you always have to check is the impedance ratio:
- between output impedance of the DAC to the input impedance of the (headphone-)preamp, and
- from the (headphone-)preamp to the power amp.
That ratio should be 1:8 to 1:10 or higher.
I know that the output impedance of a passive preamp...