Receiver phono-stage or external phono-stage??

I am using the internal phono-stage of my Mcintosh 4300V Receiver in combination with a Nottingham Horizon SE T/T, Rega 250 arm (modified) and Clearaudio Aurum Beta/S cartridge.

My question is whether or not I can improve my sound with an external phono-stage - probably a Musical Surrounding phonomena or Dynavector D-75. Would appreciate the input of other Audiogon members. Thanks for your help.
Im not familiar with the receiver, but if it's a two channel receiver and not surround sound with A/D converters that would convert any analogue input to digital, then I'd say, on general principles, yes, an external phono stage would improve the sound--depending of course on the stage you pick.
Tarsando - It is a two channel vintage Mcintosh 4300V from the mid 80's. Thanks for your input.