InvisibleInkI upgraded from an iPhone 6 to X and could not believe how much worse the sound was. I got the Earstudio BT amp (they are Dropping it again right now) and it sounds better plus has an EQ app that works.
MktgOvrCoffeeWhat are you trying to use it with? I have a few , a genuine Apple and another 3rd party dongle, they both sound fine with most IEMs. Just don't expect to power the HiFiMan HE6 with them.
MktgOvrCoffeeI have the Ugreen. It is from Amazon. Sound quality is spectacular with my KSC 75s. Sound: 26 bit/48 The review rating is higher than any other I’ve seen. Cost: $16.99
InvisibleInkI think you might be right, I tried the dongle on my wife's phone and it sounds great, something's wrong with my phone.
... and after further digging I found it. At Settings | Accessibility | Audio/Visual there's a switch to force Mono.