I agree, I also had a K5 and it has a worse HF than the KA17. They were indistinct, less resolution. Everything is fine on the KA17, after the E1DA 9038D I have no complaints about the sound quality, they play great on my Sennheiser HD660S headphones.
By the way, if you have a loud click when connecting, then delete the fiio application and everything will be fine right away. Moreover, using the equalizer you don't have a bit perfect sound, why worsen the sound? Better buy good headphones and you won't have to deal with this nonsense with the equalizer, making the sound worse.