Phono Stages with External Power Supplies...Worth It?

Can't say about the Odyessey power supply but I've ordered the $900 Gold Note PSU for the $1250 PH10 phono unit. Is it worth it? Several users say yes, hope I find it the case myself.

You've asked an impossible question.  To answer it intelligently, one would need to know much more about the differences in the power supplies between the version with the external box and the version with the on-board PS.  Can you do some research and give us more to chew on?  It's true that a large fraction of the premium you will have to pay to get the outboard PS is due to the mere fact that you are getting an extra chassis.  However, regardless of all else, having the external PS usually leads to lower noise. But if the base unit is already "quiet", maybe the extra cost is not merited.  

From what I have read in the Odyssey Forum on The Audio Circle, it is a very worthwhile and noticeable improvement. 

im Assuming the external power supply is to remedy noise. If so then would running MM carts sort of make that less necessary? 40db gain vs 55-60?

Looking at this more from a general application stand point.

It all depends. With both preamps and phono stages, separating the PSU from the line circuitry is in theory optimal. Let me emphasize in "THEORY". This is because there are phono stages and preamps with built-in transformers and capacitors (PSU's) that are superior to others that have separate with the PSU tied to the line stage via umbilical. Separating the boxes is expensive. So the short answer is that with anything less than state of the art, you are generally better off with a one box solution but not always. Generally. My Manley Steelhead has a separate PSU but there are likely (scratch that, definitely) better phono stages that are one-box. My ARC Ref 6 preamp is one-box but there is little or nothing on this planet (IMveryHO) that beats it. But then, there is the Ref 10 that sounds different, but not necessarily better.