boss gt-8 pros.. need help here..

[axisofsymmetry]

i have a boss gt8 and been using it for 2 months.. i connect it directly with a powered amp,, output selection is at headphone.. i noticed that every time i use metal distortion, feedback always appears.. can you help me with this problem?,, i need to make a good lead metal sound without any feedback.. tnx..

[Tasty]

Post it here: http://talk.philmusic.com/index.php?topic=95872.0