I don't think there's any fiction about valve amplifiers, even if there is some there should be more!
I went on "AI Fanfic Generator" a story generator, put in some keywords and it came up with this

"In the heart of a quaint northern English town in 1963, Mr. Jenkins, a stoic and meticulous man in his early fifties, meticulously tinkered away in his cluttered workshop. His wire-framed spectacles perched low on his nose, magnifying his piercing blue eyes as they danced over the intricate circuitry of a vintage valve amplifier. The gentle hum of electrical currents and the faint smell of dusty tubes filled the air, a pattern of solitude that echoed through the quiet streets outside.
Mr. George Jenkins had long been a man of passionate hobbies, but none had captured his heart quite like valve amplifiers. The warm, rich tones they produced were music to his ears, a stark contrast to the cold, clinical sound of the modern transistor-based amps that were slowly taking over the market. With a stubborn set to his jaw, he had decided that the world needed to hear the soulful sound of valves once more. His dream was to start a company that would breathe new life into the art of guitar amplification.
In the dim light of his workshop, surrounded by his cherished collection of tubes and transformers, Mr. Jenkins meticulously sketched out his vision on a large, rolled-out sheet of butcher paper. His pencil danced across the page, bringing to life the intricate schematics of his first signature design: The Roaring Lion. It would be a valve amp that could tame the wildest of rock 'n' roll spirits yet still whisper sweet nothings to the most tender of jazz riffs. His mind raced with the potential of this creation, and the impact it could have on the local music scene.
The town had seen its fair share of guitarists, many of whom had moved away to the bustling cities of the south in search of their big break. But George knew that with the right sound, they could make their mark right here, in their hometown. His plan was to offer a sound that was both unique and accessible, a bridge between the past and the present that would resonate with the youth of the day. He imagined the buzz of excitement that would follow the first public demonstration of his amp, the way the crowd would fall silent as the opening chords of a classic riff filled the air, only to erupt into applause when the sound washed over them like a warm, velvety wave.
But first, he needed to build a prototype. Hours turned into days, and days into weeks, as he painstakingly assembled the components, each soldered joint a declaration of his commitment to quality. His workbench was a battlefield of wires and resistors, a testament to his unwavering dedication. The Roaring Lion was not just an amp; it was a declaration of his belief in the power of music and the unyielding spirit of the town that had shaped him. He worked tirelessly, fueled by a blend of excitement and trepidation, knowing that the success of his venture rested upon this one instrument.
As the final tube was placed and the last wire connected, Mr. Jenkins took a step back to admire his creation. The gleaming chassis and proudly stamped nameplate reflected the pride in his eyes. He plugged in his worn-out Fender Stratocaster, his hands trembling slightly with anticipation. With a deep breath, he switched the amp on, and the soft murmur of electricity grew into a purr that seemed to resonate through the very floorboards. As he strummed the opening chords of a Chuck Berry classic, the amp roared to life, filling the room with a sound that was undeniably alive. It was the moment he had been waiting for, the first step in a journey that would take him from a solitary tinkerer to the founder of a company that would shake the very foundations of the guitar world..."