@kingofgix Soul VI will take you further in terms of leveraging ongoing evolution of your system and I don't see any reason you can't mate it with your existing system, the W4S DAC probably being the component you'll eventually come to upgrade. But Soul Supreme is definitely the more forgiving of upstream compromises (including source material), of the two speakers. Its Radian 850 supertweeter is harmonically graceful but does not equal the extended frequency response of the Soul VI tweeter. Also, if you run the Soul Supreme at its native 16 ohms impedance, eschewing parallel loading resistors, your Hegel's output will be reduced roughly in half but a lot of solid state amps sound a little cleaner and smoother into 16 ohms than into 8 ohms. It's not major but can be noticable.
One option you have is to buy Soul 6, taking advantage of Zu's 60 days return policy, and if you feel you need to back off on vividness a bit, you can order Soul Supreme if you come to that conclusion about Soul 6.
Phil