I agree that via bt it lacks a bit of bass punch and treble, and is a bit flat sounding. But everything is pretty much fixed if you use a good warm mid and bass centric amp like a fiio. Though that does defeat the purpose of having bt. Needless to say I moved on to something else, when I realised I was paying 50 bucks for bt, which I have no use for. Honestly akg products tend to need external amps to sound amazing, even though some of their headphones shouldn't need one at all.