I embedded a background audio into my website which autoplays on visit.
The source of the audio is a online stream hotlink.
Theres no volume attribute supported by browsers so you must set the volume property in JavaScript
<audio autoplay id="myaudio">
<source src="http://lel.com/link/to/stream.m3u">
</audio>
<script>
var audio = document.getElementById("myaudio");
audio.volume = 0.2;
</script>
See http://jsfiddle.net/sjmcpherso/6r1emoxq/