I have the same volume issue, but I have determined it is at the F500BT unit, not the ND-G500 amp. I know this because if i plug my ipod directly into the amp via male/male headphone connector it will go quite loud if i crank it. Also, if i plug headphones into the F500BT unit and put the volume up to 20, it is not very loud at all.
I don't know if this is normal or if i got a lemon... The volume really is quite low so I can't see this being normal - I am going to phone Pioneer support and/or stop by a service center to get a second opinion. Will let you know.
