Boy, that Luxman sounds like a keeper to me. I would be inclined to try some speaker choices. Fritz has bookshelf/stand mounted speakers that are reasonably priced and easy to drive. I saw a used pair for about $2300.
Atmosphere is selling a new Class D hybrid that gets good press.
My opinion is tubes are a pain. Hot, unpredictable and expensive. But, I have a feeling they would sound good in my system.
I am a Pass XA 25 owner and wont be changing amps. Good luck.