As many audiophiles will remember, the well-known DAC chip maker Asahi Kasei Microdevices (AKM) suffered a massive fire at their factory back on October 20, 2020 in Miyazaki Prefecture, Japan. This resulted in a shortage of their chips for awhile until they rebuilt the plant and started offering devices again by the end of 2021.
In June 2021, AKM issued a "last time buy" notification for final stock of a number of their products. This included their top-of-the-line DAC chip, the AKM AK4499EQ which was initially released in January 2019 and had made its way into a number of devices over the ensuing couple of years. By later 2021, some devices like the HiFi Rose RS150 had to transition to ESS. With 4 channels, a published THD+N of -124dB (mono mode), 137dB SNR in stereo (140dB mono), DSD "direct" (volume bypass), this chip remains a formidable converter even in 2025 with newer generations of AKM and ESS chip DACs. While audiophiles and manufacturers like to talk about discreet DACs like R2R stuff or custom "Ring" DACs, or DSD-processing DACs (like Meitner products or Playback Designs), while I'm sure they sound great, there is no evidence that these are capable of achieving better objective resolution than state-of-the-art converter chips from semiconductor companies with significant R&D resources.
For comparison, based on company specs, the current premium DAC chips are ESS's ES9039PRO rated at -122dB THD+N mono, and 140dB SNR mono. And AKM's current flagship, the 2-channel AK4499EX DAC released in 2021 listed as THD+N -124dB and SNR 135dB stereo (138dB mono). The AK4499EQ as a 4-channel DAC is a much more complicated chip than 2 AK4499EX's because it also incorporates the sigma-delta modulator internally while the AK4499EX needs to be fed 7-bit modulator data at 5.64/11.29MHz from a separate source like the AK4191EQ ΔΣ Modulator!
So, basically, as a single chip, the discontinued AK4499EQ after only about 1.5 years in production, remains the highest performing device among its peers after all these years; on paper at least.
And that's why I bought one of these for my system - the Topping DX9 "15th Anniversary" Limited Edition DAC & headphone amplifier (US$1299, CAD$1900, depending on tariffs you might do better ordering from China through AliExpress):
