BD115 as low power single ended class A single (one only) transistor amplifier

At your risk. Take all safety precautions including (military) left hand in back pocket, never working on live circuits etc. Fuse in series with battery. How would it sound at an operating point of 100V, 50mA? With output transformer with AIR GAP. (By doing some comparison on Sowter 9040s with and with no air gap , is a good rule of thumb to have and inducatance of 1/10 when a suitable airgap is created?) Bought some thin laminations of E, I type from Aristotle and Euangelos Stefos, made by Transeria Linquarg in Italy, typeGrand Orient, 0.35mm. Sylvia from Dimoulas supplied great Austerlitz heatsinks. Other candidate transistors RCA40264, 2N3114, pnp 2N5415. High volatge and low collector current operation shoulc mean low base current needed so power output should be possible by driving directly from a recorded music source just one transistor. Meanwhile the Pleiades 2N3055 single transistor amplifier in class A powered by just one 9V battery is connected to the Marantz Imperial 5G speaker given kindly by Maria and it sound Amazing with huge bass from just a 1/8W or so power amp. Smooth sound, great treble midrange and dynamis on CDs Promise - Sade, Ingenue - K.D. Lang. Single ended ECC84 poer amp sounds great tooo, possibly even smoother. Thank you Vicky, Dr. Rutter, Mr Jones.