IMO ‘yes’, and IMO only slightly.
I personally have a passion for tube gear, but hearing is of course a very subjective thing. Here’s a good article on tubes called: “Why tubes sound better”, but again, it’s all subjective, we all hear different.
Funny you should mention SMSL, I recently purchased the new “SMSL SP200 THX AAA 888” to replace my old Headroom “Little”. I’ve learned through the years to always have a Solid State amp on hand in addition to my main tube amp to serve as a ‘back-up’, and for non-critical listening. Though I will say the SMSL is proving to be super accurate and quite formidable in its own right.
The headphones I currently own are HifiMan Arya, Audioquest Nighthawk and Sennheiser HD 650’s. To my ears, the WA7 is slightly more musical and warmer sounding than the SMSL, which itself is a little more analytical sounding. Again, to my ears. This difference is more obvious on my Arya’s and less so on my HD 650’s. Whether or not the WA7 would have the “tube magic” impact on your Drop 6XX headphones to your ears or not, I can’t say.