What do I have to adjust to balance the sound? I just got my new Randall amplifier, after finding out it was my borken cord, and not my old amp that was the problem. My dad saudered the ground wire inside the output end of the cord, but to my dismay the new amp lets out a deafening squeal over my guitar. What could be the problem?

1) Why not replace the cable instead of repairing it just to eliminate it as a possible culprit?
2) Your output may be too high on your guitar or amp, allowing your pickups to, well, pick up the amp’s output.
3) Don’t stand with your guitar facing your amp, especially in confined spaces.
4) When all else fails, order a "Hush Super C" feedback suppressor from Musicians Friend.