Some units have an input labelled Phono which is only meant to take the output of an external phono stage--there's no actual phono preamp behind the input jack. However the GTP-400 is NOT like that. It has a built-in hi-level (MM) phono preamp.
But beware of inexpensive preamps, especially ones with integrated phono, an extra-cost feature. They may offer the phono feature you don't have, and with integrated phono the GTP-400 would save you a set of cables, but cheaper preamps may not give better overall sound than you're getting from your receiver.
But beware of inexpensive preamps, especially ones with integrated phono, an extra-cost feature. They may offer the phono feature you don't have, and with integrated phono the GTP-400 would save you a set of cables, but cheaper preamps may not give better overall sound than you're getting from your receiver.