You are correct, 400W is just how the board is advertised on Aliexpress/Ebay.
According to the description the board will run up to 90V rails but not recommended.
I bought a similar board a while ago, but the 300w version. Can someone check this for a short time just to check anything wrong with it? The LTspice file is just modified from the OP file, with my available component
Transistor I replaced from original design
2SA970 / 2SC2240 to 2SA992 / 2SC1845
2SD669 to 2SC2690
2SA1837 / 2SC4793 to MJE15033 / MJE15032
2SA1943 / 2SC5200 to MJL1302A / MJL3281A
I still use 2SC2705 and 2SA1145 from the original design
I don't mind change it again if it is incompatible to one another
Link to the asc file
Transistor I replaced from original design
2SA970 / 2SC2240 to 2SA992 / 2SC1845
2SD669 to 2SC2690
2SA1837 / 2SC4793 to MJE15033 / MJE15032
2SA1943 / 2SC5200 to MJL1302A / MJL3281A
I still use 2SC2705 and 2SA1145 from the original design
I don't mind change it again if it is incompatible to one another
Link to the asc file