Threshold "T" vs. "S" - whats the differences

I believe the S and SA series were made when Threshold was owned by Nelson Pass. When it changed hands the amps appearance and numbering (as well as circuits) changed. IMHO the SA series, non optical bias, were the best amps ever made by either Threshold company.

I owned the s/300 series 2( non optical bias ) and it was manufactured around 1990-1991 if my memory serves me correctly. I also believe that the "S" series was the best Threshold ever made.The T series is a later version and in my opinion once they changed from the "S" series Threshold was never the same.

T is IGBT's and S/SA series is tranny based.

loon