It’s installed in “C:\Program Files (x86)\Lame MP3”. If I tell Audacity the path to that dll, it won’t accept it. Why can’t Audacity simply allow this version to be used? I don’t want to install two versions.
When you use the “Export > MP3” option, Audacity accesses “hooks” in the LAME API and sends the audio data to the LAME library, which the LAME library then encodes before Audacity writes the encoded data to disk as an MP3 file. This method is both fast and efficient, but most standalone LAME executables do not have the necessary “hooks”, so Audacity cannot connect directly to the API.
Audacity provides an alternative method to connect to external libraries, which is to access libraries through their command line interface (CLI). Most standalone versions of LAME do support this method, but it is less efficient and does not support such close integration as API. To use this method you need to select the “(external program)” option in the Export dialog and enter the appropriate command line arguments. More information and some examples can be found in the manual here: http://manual.audacityteam.org/man/exporting_to_an_external_program.html