i recently bought a bryston 4b nrb i dont have a preamp yet. I hooked my soundcard (m-audio revolution 7.1) directly to my amp. When my soundcard is turned up all the way (there is no volume control on the bryston) the amp isnt putting out nearly what it is capable of. I asked a friend if i needed a preamp and he said the a preamp will only attenuate the signal, so it wouldnt help. What do u guys think? Im running adire he 10.1s off it.