45 single tube amp

Utilizing relatively heavier Tango OPT, 6SN7 SRPP to self bias 45 single amplifier was made about 10 years ago. The bold tone was obtained influenced mainly by OPT, not that of RCA 45, far from docility nor delicacy. As a conclusion, the balk of OPT has much to with the final amplified tone and smaller and poor OPT might result in the disappointing taste. Also chemistry and interactive balance are very important for 45 single amplifier.  Basically, I prefer 45 to 2A3.