Just don’t expect the sn to tell you everything. My 2CE Sig ‘1’s are 58328 & 58329. I assume they are Sigs as I purchased them from the second (seemingly very reputable) owner in the original boxes that are clearly labeled ‘Signature’. Unless someone was able to purchase Sig boxes during their previous ownership, I feel pretty confident in what they are. As I stated in another thread, I got them for $575 in very very good condition, complete with anchor stands (very important). That price was a no brainer for speakers of their quality and jumped on them immediately, especially after the seller sent pictures of the boxes.
Richard can be ‘all over the place’ when responding to sn questions, from, ‘we do not catalog all the serial numbers as it would cost a fortune to do so’, to answering various changes within a series by serial numbers when certain changes took place. So, go figure ;-)