The wav shield output is OK. I put a speaker on the output and the quality is acceptable. The volume control works on the speaker and the ear phone jack. I wanted more volume so I added a vm114 and a speaker that could handle the output wattage. I asked Adafruit support and they suggested a 100 microfarad capacitor in series across the positive output of the wav shield and the input of the amp.
Here are the comments:
The output of the wave shield has a DC offset. If your Velleman does not have differential inputs, you may need to add a capacitor on the input.
You connect it in series with the positive signal wire. You can use a 100uF electrolytic capacitor. Connect the positive (longer) lead to the positive signal terminal on the wave shield (that would be the ‘tip’ connection if you connecting via the audio jack). Connect the negative lead of the cap to the input of the amp.
What type of signal is the audio amp input? Thank you for any suggestion.