Bjesien,
I would say if you want clarity and detail go with the Siemens or the Gold Lions. I feel that the SED gives a softer overall sound than the other two. Between the other two in my system, i've found the Gold lions to have touch softer sound in the high end. But the bass seems to go a little lower, with better weight. They are both nice tubes and I could be happy with either one. For now i'm keeping the Gold Lions in my amp.
I would say if you want clarity and detail go with the Siemens or the Gold Lions. I feel that the SED gives a softer overall sound than the other two. Between the other two in my system, i've found the Gold lions to have touch softer sound in the high end. But the bass seems to go a little lower, with better weight. They are both nice tubes and I could be happy with either one. For now i'm keeping the Gold Lions in my amp.