Hi mate what do you mean by flat? Do you have one of these devices yourself and which settings have you used to get the best results. I have used it in the house with the surround sound system very loud, but with the line-in setup the sound is VERY dead and there does not seem to be any treble in it at all no matter what swtch I put on the sound module? Yet when I use the mic input the sound is crisp but due to the high volume the sound recording is distorted! Any ideas? tony