The Sanzer Rov zy”a testified that the holy songs composed by the Kaliver Rebbe are “kodesh kodashim.” It is known that when the Sanzer Rov would sing the song “Solo Kokosh”, his table would become soaked with the tears that flowed from his eyes.
The Chozeh of Lublin zy”a (quoted in Sefer Eser Tzachtzachos) said that the Seder night of the Kaliver Rebbe was unique in its generation and it created a light that was unlike any other in the world.