I suppose many of us are actively looking at downsizing options or will soon do so.
You have a fine system in place, and like all of us, you want your change to have as few compromises as possible.
You are lucky that your current speakers are relatively sensitive. This allows you more options that are likely to give you the satisfaction of your current system, or come very close.
The first option, mentioned by many, is to investigate a Mac SS integrated amp with an autoformer output stage. You will have the familiar Mac house sound, but loose a little of the lushness you probably enjoy from your tube based system.
2nd option would be Class A Luxman integrated amp. This will likely get you very close to the sound of your current system, and includes an excellent phono stage which may allow you to remove another box from your system.
3rd option may be an Accuphase integrated amp. I only know what I have read, but I think it would worth your time to investigate.
4th option would be a Tube Integrated amp; either a Leben 600 series or Aurorusound HFSA 1. BOTH would work well with your speakers, and provide the tube sound that you enjoy with your current system. However the system would not play as loud as you may be used to.
If it were me, I would choose either a Luxman or Leben integrated and be set for the next 10-20yrs.