I think Viridian's and Stan's suggestions are good. To explain what Elizabeth and I were saying, generally a phono stage is used to accept a very low level, comparatively weak, signal from a phono cartridge and amplify that signal. Thus , there is an amplification stage in the phono stage that, were you to feed it a signal that is too strong, would overload the unit. The RIAA equalization is also built into a phono stage--records were intentionally cut with reduced low frequencies so they could be cut on the record and played back by a stylus (I'm oversimplifying--I'm sure other frequencies were intentionally changed during the cutting of the record)--the phono stage has a built in equalizer to attempt to restore the frequencies to what they were on the master tape. If you play back a source like a CD that was not "reverse equalized" like a record was, it will skew the frequency response of the music on the CD.