This plugin is great but when I used it, it displayed value=\"always.
There's a line break hidden in the code, line 94 of soundcloud-shortcode.php.
Just get to the end of the line, press delete to make the line no read:
"\"></param><param name=\"allowscriptaccess\" value=\"always\"></param><embed allowscriptaccess=\"always\" height=\"" .
Save it. Job done.