The Sample Editor allows the use of AudioSuite plug-ins. These plug-ins work destructively—the result of the editing process is written into the audio file.
Note: AudioSuite plug-ins can only be used with hardware addressed by the DAE (Digidesign Audio Engine). Any properly installed AudioSuite plug-in will be displayed in the AudioSuite menu.
Are you running Logic under DAE with Digi hardware, or are you running under Core Audio? You need to be running under DAE before any available audiosuite plugins show up.