This Chinese transformer was bought in order to build a headphone preamp with one or two driver tubes (6N23P, ECC88 or so) and the cathode follower based on 6N5C (6AS7). The specifications say: Sec.: 170V 3A and 6.3V 5A. In practice, the load of 2.5A already lowers the heater’s voltage from 6.4V (idle) to 5.95V, which makes that transformer useless for that kind of project. It still can be used for some simple preamps with 2-3 tubes with 0.3A heaters.