You would need to use a preamp, have the CD output lowered, or you could find an amp with a lower input sensitivity...that probably matters more than its actual power rating (since a 180 watt amp should only be twice as loud as an 18 watt, assuming other things being equal). There is also a chance that someone makes (or will make...custom) analog attenuators with resistors to work with your CDP's output level (something like the EVS ultimate attenuators). It's an option that would be cheaper than a good preamp and probably sound better than your digital volume control, if done correctly.
