Just bought a Ray 168 to replace my three year old Droplet, which had it's transformer fry from a power problem at my house...sounds good out of the box, more resolving power than the Droplet...bass appears to be in same league or even deeper and more detailed but I don't appear to be losing anything with this change. Not sure of Prima tubing but different output tubes have different sound signatures and any demo you can to with your own gear (probably not possible) is the ultimate way to go.
Larry
Larry