I agree with you 100%. The amplifier affects the sound signature the most. That's why I also thought that the 320 with Rohm and in connection with Amplifier 12 EX/EXN is at least on the same technical level as the M 9 or maybe even a bit higher. I'm not talking about the sound signature, whether warm, transparent, natural or bright. That remains to be seen.
Not to mention when it comes to audio, the diminishing returns shoots up once you reach the $1k mark.
DX300 already reaches the peak of diminishing returns for DAPs. While others might find significant difference between DX300 and N8ii, to me that significant difference is maybe only 5%
It is harder to measure auditory than visual differences. I can easily notice the difference btw 1080p and 4K, however I’ll be hard pressed to hear the difference btw 16 bit and 24 bit recordings.
If given the choice though, I would pick FiiO M17 as the best valued DAP/transportable out there.