You answered your own question quite well, it's the implimentation that makes the difference. However, if we make that implimentation equal, the latest AKM chips are tagged "Velvet Sound" and that's a pretty good description in my experience. The ESS chips have traditional been on the clear and insightful side, but the latest round has moved in the direction of a more genteel presentation. Personally I like both my ESS and AKM dacs, but they're different for sure. Caveats are I haven't a clue what's going on with the fire at AKM, they stated they're not rebuilding the plant, but there's a zillion new product releases containing AKM chips. I'm assuming they've been outsourcing production for some time, but I don't know anything as fact. The other caveat is the infamous midrange bump in ESS chips appears to be gone in the latest generation. I don't know how far down market that goes, but according to ASR it's not apparent in the 9038 series. Manufacturers picking chips for low and midpriced AVR applications are looking for a lot more functionality as well as low cost than a designer of a stand alone audio DAC might. And going back to the beginning, the implimentation of that DAC in a receiver is going to be a lot different than a separate DAC. If you got pretty good digital performance from a mid priced receiver I'd call it success.