I bought these headphones for the noise cancellation capability to try and help keep the volume level as low as possible and protect my ears from further damage (I'm only 35 but have severe tinnitus and hearing loss from listening to headphones too loud).  However beyond that I want to be as safe as possible and follow recommended safe listening levels for certain decibel exposure levels when using my headphones. All I can find from Sony is this from the manual:

SENSITIVITIES (DB/MW) 104.5dB / mW (1kHz) (when connecting via the headphone cable with the unit turned on) , 101dB / mW (1kHz) (when connecting via the headphone cable with the unit turned off)

But this is really not intelligible or usable to the average person. I have no idea how to interpret it. In order to do actually have usable information I need to get to something like an estimated db level for listening to music at given volume levels e.g. dbs at max/average/min or better at 25%, 50%, 75% 100% volume.

In anyone's experience has Sony ever provided this, or can help calculate it based on the information provided? I understand that there will be factors like it might output more volume plugged into PC vs wireless on a mobile, but some guidance better than something. 

I just want to use my headphones without anxiety every time.