You used the term LP in your title and record deck in your post. I am going to assume you mean that you have a turntable, playing LPs (vinyl records) attached to your stereo?
There are 2 types of cartridges used in turntables (the cartridge is the part attached to the tone arm that contains the needle or stylus). The first type is referred to as ceramic while the 2nd type is referred to as magnetic. The two types require different inputs. The magnetic cartridge has a much lower output than a ceramic cartridge so there needs to be an additional pre-amp stage for a magnetic cartridge.
Since you are stating that the volume is too low, I suspect that you have a magnetic cartridge and it is plugged into a ceramic phono or even an aux input. Check to see if your stereo has an input labeled "Magnetic Phono" or something similar to that. If not, you need to purchase a "Magnetic cartridge preamp" such as this one: http://www.radioshack.com/product/in...ductId=2573420