Depending on who you listen to, these are either ‘Uber’ CCa tubes, or near-spec. tubes that are close but not quite linear in circuits designed for 6DJ8 tubes. Well thanks to the subjective nature of audio, they’re both! Before sharing my thoughts, here’s what’s said about E288CC tubes by some of our well known audiophiles… Joe’s Tube Lore says… Siemens E288CC (with shield, gold pins) More...