Can you imagine perfectly stable operational amplifier made with thermionic valves (tubes), ECC81, ECC82, ECC83. Amplifying DC millivolts to stable volts and co

Can you imagine perfectly stable operational amplifier made with thermionic valves (tubes), ECC81, ECC82, ECC83. Amplifying DC millivolts to stable volts and converting them to pressure 3 - 15 psi, because intrinsic safety circuits were not possible at that time. 4-20mA came later.