Both Harbeth and Spendor will sound great with the VTL.
I would not recommend the ATCs, which favor the purer sound of solid state over tubes due to their neutral design.
You might also want to audition Zucable speakers. The Zu Tones and Druids are very dynamic and lively and have an overall warmth to them--lot's of tubey magic on the ones I have heard at tradeshows. They might match well with your system and are priced about the same as your speakers above.
As a safe bet, you should also contact VTL directly and see who they use for demo purposes.
I would not recommend the ATCs, which favor the purer sound of solid state over tubes due to their neutral design.
You might also want to audition Zucable speakers. The Zu Tones and Druids are very dynamic and lively and have an overall warmth to them--lot's of tubey magic on the ones I have heard at tradeshows. They might match well with your system and are priced about the same as your speakers above.
As a safe bet, you should also contact VTL directly and see who they use for demo purposes.