What kind of headphones amplifier for Yamaha R-S201 and how to connect
thanks
Is there something wrong with the existing headphone output? It's easier to make a recommendation if we know what problem you're trying to solve.
If the headphones are not loud enough or if you've got an "impedance problem" any headphone amp with line-inputs can be plugged into the existing headphone output (with the appropriate cable-adapters).
Or, you can plug into the "tape outputs" or "recording outputs" if your receiver has them, but these are not volume-controlled so you won't be able to use the receivers remote control for volume. (Bass & treble, EQ, or other controls/adjustments will also be bypassed.)
I don't have a recommendation for you but I'd recommend that you don't spend a lot of money (unless you have lots of extra money and you don't care). The actual electronics for a good headphone amp are cheap & easy so you're mostly paying for the power supply, case, controls, connectors, marketing, etc.