I often wonder (as in shake my head) at phono preamps. They have a simple, and in today's world of available components, reasonably easy to accomplish tasks:
take the signal from an MM (or occasionally an MC) cartridge and boost it up to a few volts to drive a preamp or amp that doesn't have the needed gain or RIAA equalization. It's best if the phono preamp has an input impedance to match the cartridge manufacturer's specs -- and an output Z that will drive the next amp firmly and correctly.
The source can be presumed to be a vinyl disc (here come the vinylphiles) which, under real conditions, has a frequency response of about 25 to 15000 Hz and a dynamic range of no more than 60 dB on a good, clean, early pressing. Figuratively, modern, reasonable-cost electronics should be able to do this with easy grace.
To a good designer, this is pretty trivial. Yet audiophrenics will obsess over it, and opine that any perceived difference between devices is "better."
(No, it's just "different.") It's like changing the color of chess pieces from white to gray, or black to dark green. The game is still the same.
To reproduce the sound imprinted on a vinyl record can and is done with preamps built-in for free, outboard devices for $75-$350, and foo-foo "high end" devices costing thousands. I'm pretty sure that, if a proper double-blind testing procedure was ever in place, trained listeners would hear differences, but not be able to judge cost with any correlation. As it is, it's all a fashion show. And the use-case is more like sweatpants. A Nike swoosh won't make you run farther. A milled aluminum billet front panel does nothing to change the function. Just the price.
Execute a double-blind testing program with trained listeners, and try to prove me wrong.
-Just one man's view.