7
You could do it via commandline:
cscript.exe wmcmd.vbs –input inputfile.wav –output outputfile.wma -a_mode 0 –a_setting 56_44_2
-a_mode mode_number
Specifies the encoding mode for audio content. You can use one- or two-pass CBR encoding (-a_mode 0 or -a_mode 1, respectively), or a VBR encoding encoding mode: quality-based (-a_mode 2), bit rate-based (-a_mode 3), or peak bit rate-based (-a_mode 4). For more information, see Using CBR or VBR encoding.
-a_setting bitrate_samplerate_channel
Specifies the audio bit rate, sample rate, and channel setting for encoding. Or, if you are using the Windows Media Audio 9 Professional or Windows Media Audio 9 Lossless codecs, -a_setting also specifies 16- or 24-bit encoding, as bitrate_samplerate_channel_bitspersample. Use the -a_formats option to view the settings supported for each codec. If you are using the Windows Media Audio 9 Voice codec, the default value is 12_16_1. If you are using the Windows Media Audio 9 Professional codec, the default value is 128_44_2_24 (unless you are also implementing a quality-based VBR session, in which case the default is Q75_44_2_24.) If you are using the Windows Media Audio 9 Lossless codec, the default is Q100_44_2_16. If you are encoding uncompressed content, the default value is 705_22_2. For all other scenarios, the default value is 64_44_2.