I was actually referring to three things:
- DSD HF Noise Filter (which cannot be bypassed as far as I can tell).
- D/S Modulator (bypassed only if DSD Direct is enabled and Attenuation is Disabled)
- Reconstruction Filter
The question is, how are Topping configuring the 4499 for DSD input. If they’re using pin-control mode, then the digital attenuation is enabled, but locked at 0 dB, and the D/S modulators are in the path. If they do it using register-control mode, and enable DSDD=1, then the digital attenuation is completely bypassed and the D/S modulators are not in the path.
One would hope (even expect) that they’re using register control mode, but short of Topping confirming that, or having a unit here to mess about with, I can’t say.