Id have to agree with Mr Softdome.
Find the speakers that really get you going and decide if you want the lower line towers over the higher line bookshelfs or vice versa.
Personally, if youre set on the Hsu VTF-15H, AND you decide to go with bookshelf speakers, Id go with bookshelfs that have can produce good bass on their own. Speakers Id consider:
Paradigm Studio 20s
Monitor Audio RX2
Im not that big on the PSB Imagine Bs as I felt their bass response was weak. Ive never heard the Ascends, so its a blind faith recommendation based on forum talk. All these speakers in that price range will have their strengths and weaknesses, it will just be finding what works best for you.
Dynaudio Focus 260s, Focus 210C, DM 2/6, Hsu VTF3 MK5 HP, Oppo BDP-103, NaimUniti 2, Naim Stageline N, Pro-ject 2xperience Classic, Marantz SR7007, 60" 4K Samsung LED LCD