Thank you for your inquiry about the new design change.
Please check our blog posting below:https://www.qudelix.com/blog/akm-and-ess
Both AKM4377a and ESS9218p are good enough to deliver the same sound quality as long as the application is designed and implemented correctly.
Both DACs require a precise external clock. At any given DAC, the external clock defines Sound Quality much. In terms of application viewpoint, ESS allows the application to use more wide variety of clock frequency. So, we can choose not only audio clocks but also very precise RF clocks for ESS DAC, for example.
And ESS9218p provides eight types of digital filters.
We're designing 5K DAC/AMP with every technical benefit of ESS9218p, and the final application would deliver the best Sound.