When I start k3b I get info about 1 problem in "System Configuration Problems". This is: "Mp3 Audio Decoder plugin not found." I don't worry as I am not going to burn MP3 as CDA.

I click "New Audio CD Project" and then I drag & drop my 10 WAV files into AudioCD0 project. This causes unexpected message: "Problems while adding files to the project.". When I check for details I can see:

Unable to handle the following files due to an unsupported format:
You may manually convert these audio files to wave using another application supporting the audio format and then add the wave files to the K3b project.
/home/zajec/shared/DW_A0007.wav
/home/zajec/shared/DW_A0008.wav
/home/zajec/shared/DW_A0009.wav
/home/zajec/shared/DW_A0010.wav
/home/zajec/shared/DW_A0011.wav
/home/zajec/shared/DW_A0012.wav
/home/zajec/shared/DW_A0013.wav
/home/zajec/shared/DW_A0014.wav
/home/zajec/shared/DW_A0015.wav
/home/zajec/shared/DW_A0016.wav

OK, let's make sure theses files are in WAV format:
zajec@linux:~/shared> file ./DW*
./DW_A0007.wav: RIFF (little-endian) data, WAVE audio, IMA ADPCM, mono 22050 Hz
./DW_A0008.wav: RIFF (little-endian) data, WAVE audio, IMA ADPCM, mono 22050 Hz
./DW_A0009.wav: RIFF (little-endian) data, WAVE audio, IMA ADPCM, mono 22050 Hz
./DW_A0010.wav: RIFF (little-endian) data, WAVE audio, IMA ADPCM, mono 22050 Hz
./DW_A0011.wav: RIFF (little-endian) data, WAVE audio, IMA ADPCM, mono 22050 Hz
./DW_A0012.wav: RIFF (little-endian) data, WAVE audio, IMA ADPCM, mono 22050 Hz
./DW_A0013.wav: RIFF (little-endian) data, WAVE audio, IMA ADPCM, mono 22050 Hz
./DW_A0014.wav: RIFF (little-endian) data, WAVE audio, IMA ADPCM, mono 22050 Hz
./DW_A0015.wav: RIFF (little-endian) data, WAVE audio, IMA ADPCM, mono 22050 Hz
./DW_A0016.wav: RIFF (little-endian) data, WAVE audio, IMA ADPCM, mono 22050 Hz