The rear input sensitivity on the X1800 is not currently adjustable. They recently appropriately reduced it, something the MP2015 is greatly in need of, but did not make it fully adjustable like on some of the older Denon DJ models like the X1700. For instance, a 0dBFS SPDIF input signal meters to about -15.5dBFS on the X1800, which is pretty comfortable at just a few dB above the meter zero (0dBVu) that’s about -18dBFS below the digital brick wall, IMO, but having it adjustable would be useful for widely differing output levels. If they ever add a -6dB pad on the Prime players and don’t make the X1800 input levels adjustable for each of the input types, then I hope they will at least change this from -15.5dBVu to -10. Adjustable would be better, though. I’d be curious if you’d run out of gain/trim knob boost. I suspect you haven’t yet and this is just a matter of personal preference, not that there’s anything wrong with that.