I agree, it is a modern sounding tube amp. The dense presentation will appear after a few hours, least that is what I found, you will find the sonic landscape packed with detail once the amp burns in a bit.
Also tube rolling will help a bit with this though what tubes has Shikada san put in yours? It looks like he is stocking new amps with lovely mil-spec US tubes which need a good twenty hours or so of burn in to come fully on song, truth be told most of these types of tubes need that, you will find the amp really opens up.
As far as tubes to help go really deep in the mix I find a combination of either Phillips or Mullard in the DL92 and German tubes in the DF91 give a really good balance of weight and detail. Though it has to be said my favourite right now is the Phillips/Mazda combo for absolute detail retrieval but at the same time weight and depth but these are fine tuning, ultimately the amp stays in my experience a very clean amp and also revealing, its the micro details that I love that this amp portrays but not at the expense of the performance as a whole.
The PF's I feel find their natural amplifier home with this amp!
I am so glad your happy with it, wonderful!