I was blown away by the 2 quads of blue glass KT-88's that I installed in my VAC Phi 300 that I wanted the full complement. Galen Carol audio's website gathers first-hand experiences of the 6SN7's, and the qualities described there are what I'm hearing in the KT-88's.
There's an unmeasurable magic that caused my eyes to well up last night - yeah, the real rare magic of music. In Anne Sophie Von Otter's 'Sovente il sole' (Vivaldi) there's a moment when her voice emanates from the same note at the same moment the violin plays it. Purest beauty.