Study ValveAmplifier D.I.Y but in Spanishgood for you.old Argentina book.
Single Ender EuropaEDERER EDERER Amplifiers
Vintage circuit from UK about Old Europian Radio'sCircuits
Main Site of VintageRadio and Electronics
By Google translate
How about use for sound source from Raspberry Pi B+ This is not toy..High End Audio

Only in JapaneseRadio Boy
Where can you buy EL3N NOS
from Europa also can buy Japanese Transformer and components
since 21st May 2011.last up date 13rd Jan 2023 from Sakura Chiba Japan

Single Ended Amplifier D.I.Y
How to build up Amplifier Single Ended Amplifier 2003-2023