You can't take measurements at face value when you know their conditions. As I understand, the 0.003% THD rating was a baseline test from the first prototype of the Wave, which was basically a Geek Out with a battery. Larry also does measurements of THD with a 32 or 16 ohm "real-world" load, I believe, which will make things look "bad".
I'll bet that the P1 here was taken with no load, as the THD is just 0.0002% more than than reference specs. My bet is that with a 16 or 32 ohm load, those numbers will go up --- still very good, but not ridiculous. Initial test results of the Calyx M, which also uses a single ES9018-2M as well, touted 0.0008% THD with no load, but that number went up to >0.003% with a 16 ohm load.
The Wave's 116 dB SNR is also a direct transplant from the Geek Out, IIRC. A dual DAC or dual mono XD will get a 3 dB boost in SNR; also, most people prefer to do the -60 dBFS dynamic range test, so that soft muting doesn't artificially boost numbers, so we don't know how the two compare directly.
Let's say today that you got the dual DAC and THD package for the Wave; that means that even with the conservative 0.003% measurement, you'll be getting 0.0015% THD with a challenging low-impedance load, and >119 dB SNR. Seems like it'll start to look a bit more comparable in terms of performance.
I'm not trying to diminish the P1 --- it looks like a really great DAP, and it looks like a better value than the AK120 II and AK240, IMHO, and I actually think that the PCM1792A and the ES9018S (not talking about the 2M) are on pretty equal terms with regard to performance. It's just too early to tell for the Wave, while the P1 seems slated to come out within the next couple of months, so these numbers are pretty final.