audiofilo123 - the 'funny' part about your Copland amp comment is that Thiel speakers require current-source power rather than the ubiquitous voltage sources. An amp that will drive a Thiel, including your little CS.5s, should double its 8 ohm power rating into 4 ohms and at least 1.5x its 4 ohm rating into 2 ohms.
The Copland might do well with higher impedance speakers, but not have the current delivery capability that your Thiels require.
Frustrating? Maddening? Yes. Solvable? Yes.