Es9028Pro is still Top tier Chip. It has even higher specs than AK4497EQ (found in Cayin N8 and AK SP1000...etc...). The only thing that is higher on the market now would only be ES9038pro. AK is barely playing the catch up games as they just recently announced AK4499EQ. The 28Pro inside the Dx200 and Dx220 is very hard to implement (for a portable), and there are only 2 of the kinds on the market at the moment using Dual Chips, and both is Ibasso. They are Dx200 and Dx220.
My observation is that, while Ibasso is on top of the game, and there is no competitions, why change up ? Newer DAC will means the whole completely design and architecture from the ground up, which will inflate the price quickly. Ibasso goal for Dx220 is more likely an upgrade to an already excellent platform without competition on the market, from Dx200, upgrade into 220. The Dx200 is 2 years old and still has no competitions, and so the 220 is an upgrade to that.
For what you are asking, it have to be Dx300 as another line, higher tier...etc...
Once again, DAC-IC Chips is only a marketing point, so don’t let it fool you. There are still Devices with ES9018S that is going with MSRP of $6,000, for example, the Yamaha CD-S3000. Please, do not fall into the simple category where a simple DAC-IC marketing would make or break the purchase decisions. The DAC-IC alone can not do anything by itself, period.
Would you ask Sony DMP-Z1, at $8,000 MSRP the same question...why using cheap AK4497EQ X2 as the same as Cayin N8 ?