I bought an SMSL D400EX, which theoretically supports Direct DSD mode at 512 rates. Unfortunately, I'm getting a strong hiss in the background of the music at DSD 512 rates. At DSD 256 rates, the hiss is still there in the background, but faint. I can't seem to find any combination of options that gives me the clarity of PCM with no background hiss. Disabling Direct DSD mode on the D400EX fixes the issue, but I believe that signal gets converted to PCM internally when direct DSD is disabled, so no point in that. Might as well just do PCM upsampling.
Has anyone here successfully used the SMSL D400EX with HQPlayer in direct DSD mode?
EDIT: Looks like the hiss is significantly reduced if I select Sound Color 3 or Sound Color 4, both of which run the chip at 11M vs Sound Color 1 and 2, which run the chip at 5.6M. Weird, but glad I found it. Still not totally clean though.
EDIT2: OK, finally found that with Sound Color 3 and 4, DSD rate 22.5792 MHz, I can't tell the difference with Direct DSD Mode (Fixed DSD Bypass Pre Mode) on or off in terms of background noise. Using 44.1k x 512 bit rate /limit, 48k DSD option unchecked, with ASDM7EC-super 512+fs, poly-sinc-gauss-long for 1x and poly-sinc-gauss-hires-lp for Nx. Sounds fantastic.