The more I use Lotoo PAW S1, the more I like it. There's definitely different between S1 with ifi Hip DAC and Zen DAC due to different DAC chip but all of them have good SQ. It's so easy to drive my 1more H1707 (unbalanced) and Hifiman HE400SE (balanced) with details and clarity.
With iFi Hip DAC you have to worry 2 batteries, the phone and the DAC while S1 you only need 1
Both can play Hi-Res, DSD and MQA
Hip DAC you can't change the sound signature except in the phone where you'll loose the bit-perfect but S1 have the built in EQ/ATE except for MQA
Both can control volume externally
S1 you have the display of information while Hip DAC based on LED color (PCM/DSD/MQA)
Both well built with aluminum casing
S1 is more portable and worry free compare to Hip DAC without hassle
S1 will not easily forgive bad recording files
This small dac/amp have checked all the box as a truly portable device that can enhance you music listening level while on the go. Good work Lotoo!!