1. Okay, De-Popper has done a swell job of removing most of the clicks and pops from our files. Now we are going to reload each and every file in Audacity, listen to it carefully, and remove any clicks that De-Popper might have missed. Finally, we are going to adjust (normalize) the volume of each track and export (save) it in the form we desire, such as mp3.
2. The process of zeroing in on clicks with Audacity may seem a bit clunky at first, but as you work with the software, the process gradually becomes easier. What we will do, after hearing a click, is stop the playback and select that portion of the waveform that contains the click. We will then play that portion, and re-select another segment that contains the click, and so on, until we can isolate the click in a fairly zoomed-in display that will look something like this:
Single click in left (top) channel only at 22.295
Note that percussive events like light rim shots can look very much like clicks, so we cannot rely on our eyes alone in identifying these unwelcome transients. Anyway, to get rid of this click, we will narrowly select just the click (it's okay that the undamaged channel is included in the selection), and then we will select "effect/repair" from the menu bar. The click should then magically disappear. Or, as may happen, we may get a message that says "The repair effect is intended to be used on very short sections of damaged audio (up to 128 samples). Zoom in and select a tiny fraction of a second to repair." All this is telling you is that you have to narrow your selection and try again. The nice thing is, once you have successfully repaired one click, from then on the keyboard command "control+r" will work to eliminate any click you have properly selected (meaning you don't have to go through the menu bar selection again). Note that if we have a very narrow damaged spot that for whatever reason the "repair" effect will not fix, we can usually safely select it and delete it without any noticeable audible effect.
5. After we have repaired a track to our satisfaction, we can go ahead and adjust the volume to its maximum safe level without clipping. Select the entire track by zooming out totally (control+f) and then pressing control+a. Go to Effect/Normalize. Leave the control box that appears with its default values (both check-boxes checked, and the maximum value 0.0). Press OK. The software will amplify your track so that the maximum amplitude in the waveform does not exceed the clipping point of 0.0. If you find that one track or the other needs additional amplification, you can go to Effect/Amplify left or right channel. (This is one of the additional free effects we installed when we first downloaded Audacity). This permits us to amplify one channel only by any amount we specify, while leaving the other channel alone.
6. After we have finished adjusting the volume of our track, we can finally finish up by saving it as, for instance, an mp3. First go to Edit/Preferences on the menu bar. When the preferences control box appears, click on "file formats." In the MP3 export format bit-rate box, select the bit-rate you would prefer to use (I generally use 192 for vinyl restorations). (This is assuming that you installed the excellent lame mp3 codec as I suggested when you first installed Audacity.) Click OK. Now go to File/Export As and save your mp3 file in the folder of your choosing. Note that the file command we have grown accustomed to think of as "Save As" is "Export As" in Audacity. "Save Project As" is for saving an unfinished project so that you can continue it at a later time.