Df player volume

I am working with the DF player Mini and decided to plug in my Sennheiser hd650s. When I played the music I expected it to be very quiet since the headphones are 300ohms. Instead, it was very loud. Does anyone know how the Df player mini was able to power them?

I found the HD650 user manual online and it says 97dB SPL at 1V RMS.

The DF Player can probably put-out more than 1V RMS, and since it can drive a speaker 300 Ohms is no problem. (If you've got both sides in parallel that's 150 Ohms.)

Thanks. I really don't know a lot about audio.

From what I can find it has volume level adjustments, simply turn it down. If it does not have that then add a resistor in series to each speaker, start with about 100 ohm then adjust until you get what you want. If it is to loud increase the resistance.