Thomas, great write-up and photos, thank you!
Your comments and conclusion largely resonate very well with what I hear as well.
I also appreciate you transparently mentioning your business relationship with Spirit Torino as a distributor in your review.
Would be nice if you make full disclosure of this by adding the MoT (Member of Tribe) of your company in your signature or profile
A finely grained amp, with clean, tight bass pristine and ultra-high resolution is what I would recommend for amp matching, and I agree that the Valkyria need more quality than quantity.
The Egoista 2A3 and THA2 mentioned above must be phenomenal pairings, and I also suspect the additional grunt of a Viva 845 does not add much value to the Bartok internal amp in this context.
@mammal could give a first-hand confirmation to these speculations.
This is very possible, as Spirit Torino used a similar Audio GD stack during the development of the Valkyria.
Spirit are strong believers, and also resellers - again, for full disclosure - of Kingwa products.
Close to 700 grams, actually the headband distributes the load on your head pretty evenly, but of course you clearly feel them when you wear the Valkyria.
That does not prevent me from multiple hours straight of listening, by the way