"Also, as I'm totally new in this thing, will a pure Class A tube amp with 18 Watt sufficient for my room?"
Good quality small speakers with extended bass, like these KEFs, tend to have very low efficiency and all like power and current, the more the merrier, for best performance. 18 watts is minimal to drive most any speakers except those that are upper echelon in regards to efficiency. High efficiency speakers with good bass extension will tend to be larger. That's basically how it always works based on teh laws of physics.
I've heard teh KEFs off my 180 w/ch and 500w/ch amps. THey sounded excellent with the 500 watts in my smaller 12X12 sunroom. They did not impress at all off 180w/ch in my larger family room area.
So I would not expect much out of the KEFs with 18 watts no matter how they are boiled.
Good quality small speakers with extended bass, like these KEFs, tend to have very low efficiency and all like power and current, the more the merrier, for best performance. 18 watts is minimal to drive most any speakers except those that are upper echelon in regards to efficiency. High efficiency speakers with good bass extension will tend to be larger. That's basically how it always works based on teh laws of physics.
I've heard teh KEFs off my 180 w/ch and 500w/ch amps. THey sounded excellent with the 500 watts in my smaller 12X12 sunroom. They did not impress at all off 180w/ch in my larger family room area.
So I would not expect much out of the KEFs with 18 watts no matter how they are boiled.