I can now state with confidence a few things on this subject:
The X1800’s sample rate conversion, particularly the upsampling, is significantly inferior to the X1700’s interpolative variety. If you input 44.1khz SPDIF into the X1800 when the mixer is set to 96khz, you’re just mucking up the signal. The X1800’s upsampled highs in particular sound like there’s some upper octave strangeness going on and it’s just not as pristine overall.
The overall processing of the X1800 (can’t say if it’s the clock or the maths or what) is maybe very slightly inferior to the X1700, but some of the choices made on things like the EQs and the novel iso bypass makes the X1800 quite a bit more transparent in some respects to the original digital signal for a number of reasons other than the overall processing. If you put the same sample rate into the mixer as the mixer is set at, the X1800 just sounds a tiny bit dry and the mids have a teensy kind of recessed or withdrawn flavor that’s not as expressive as the mids originally were in the SPDIF stream if you compare using a common outboard DAC and the X1800 in and out of the path. In such a scenario, the X1800’s SPDIF out when not using effects is at least as transparent to the original SPDIF input as any mid-fi consumer digital home theater receiver. When not using the SRC on the X1700, much of the difference in sound is its isos coloring the signal in a pleasing way, with the rest mostly seeming to just be the slightly better mids’ processing on it. Let me put it this way… the X1800’s core processing is accurate enough to at least hear SRC effects… on the players, on the mixer, on your computer after recording and playing back with an OS mismatch, etc.
Using the lower sample rate settings on the X1800 with the Prime players’ current SPDIF produces additional sample rate conversion (SRC) artifacts that are less-than-desirable except for one aspect: the Prime players currently wildly resample everything themselves, the layer and SPDIF don’t change to match the file being played, you can’t change the rate the layer and the SPDIF are running at manually to match your files, and the SPDIF is always at 96khz. The SRC on the Prime players produces intermodulation and nonlinear distortion, including some ultrasonic garbage that can reduce the performance of downstream gear like amplifiers, headphones, and tweeters… probably even the X1800’s own headphone jack is having a performance drop from the ultrasonics. If you set the X1800 to a lower sample rate than 96khz, while it adds some distortion of its own, it will also roll off that ultrasonic garbage. So you sort of have to pick your poison when using the Prime players with the X1800. This probably also explains why using the Prime players with certain analog mixers that naturally roll off the audio over 20khz might seem more pleasant in some ways right now. The X1800 at 96khz is accurate enough to fully reproduce that ultrasonic grunge from the Prime players’ current processing.
Listing these threads below so people can find their way back to this post here later:
https://community.enginedj.com/t/the-sound-of-the-x1800-tell-me-please/