It's a common problem. Most CD players and many other sources put out such a high signal level that the volume control on the amplifer can hardly be turned and the music is too loud. And there's a lack of fine control at lower levels.
Attenuators are the answer. These audiophile devices simply plug into any input sockets and reduce signal levels by 3dB, 6dB, 10dB, 12dB or 20dB. They can be used with integrated amps or pre/power amps, and are compatible with equipment over the entire price spectrum, from budget to extreme high end. Rothwell Audio Attenuators are recognised as the leading brand.