Volume level of ARC Ref 5 seems very high

The Ref5 does not use a mechanical attenuator. It is microprocessor controlled.

This is not something I normally do so you would have to contact the factory. Changing the overall gain of the line stage could change the sonic character as well. The other issue involves changing the overall gain for those who play vinyl and have separate phone stages. Since you would have less gain in the high level stage that could cause a gain issue depending of course on the cartridge you use, speaker sensitivity etc. There is no easy solution. To cause the least amount of sonic damage, changing the gain on the CD input may be a better option.

Newbee, there is no simple answer. For example, in my situation I would prefer a unity gain i.e. 0 gain remote controlled device as my audio and video system are one in the same and I can't use my ARC SP3C. I refuse to get up to change the gain or mute the preamp every time I change channels. I don't feel like building one either.