They can be as liquid as the hd650, as well as lush. I feel they are also very forgiving for the level of performance they give. It's an upgrade in every aspect. However they are more revealing of the sound signature of your downstream gear. It's gonna get through, for better or for worse, but imo, it's never gonna sound bad nor not good enough. The hd650 scale with gear that matches them better as well. It really depends which way you wanna go in spending your money.I have entry level stuff. I drive my HD 650s with the modi/magni combo. The sound is liquid and lush. I have tried many headphones and none of them had that liquid sound. I have been eyeing the clears as an upgrade for my HD 650s. I wonder if they have that liquid and non fatiguing sound.
Imo, it's very likely you won't use your hd650 beside the Clear. It just kills the hd650. Well, unless you really need that super forgiving sound the hd650 has.
Depending on gear matching, on the Clear, I guess soundstage can be cozier. Other than that, it's just pure PRaT and nice punchy tonal realism.