In the vast majority of cases, the sound quality of the DUDU7 head unit is definitely superior to the original factory head unit. This sentiment is echoed by most DUDU7 users, who acknowledge the excellent audio performance of this unit. I would recommend reaching out to your dealer for assistance in checking the connections of your audio system.
It's unusual that you are experiencing artificial-sounding audio with the DUDU7 compared to your previous S160 unit, especially given the positive feedback from other DUDU7 owners. The TDA7803 amplifier in the DUDU7 is generally well-regarded and delivers high-quality sound reproduction.
Before concluding it is a problem with the DUDU7 itself, I would suggest having your dealer carefully examine how the head unit is connected and integrated with the rest of your car's audio setup. There may be an issue with the wiring, speaker connections, or configuration settings that is degrading the audio quality in your particular installation.
With proper installation and setup, the DUDU7 should provide excellent, natural-sounding audio that surpasses most factory systems, as attested to by many satisfied users. Work with your dealer to troubleshoot and optimize the system before resorting to reinstalling your old unit. They should be able to identify and resolve any problems to get the best performance out of your new DUDU7 head unit.
Given the strong track record of the DUDU7, I'm confident that with some expert assistance, you'll be able to enjoy the great sound quality that so many other owners have experienced. Wishing you all the best in getting this resolved!