Turntable Ground Wire question

Sure you can try that. No harm, no foul. But I think you will probably find this creates too much hum to be worth the tiny bit of time and effort saved. 

As for EQ, everyone nowadays has long since settled on RIAA. So there is today really only the one RIAA curve for all records. Go back far enough in time though, this was not always the case.

This isn't my specialty but back when a lot of the 78s were made there were a lot of different equalizations in use. You practically have to be a historian to research this if you really want to play these back accurately. 

In fact if it was me, I would do this research first. Then I would compare the 78s I have to today's RIAA. Then of course I would also listen to them. Because like everything else this is a world of trade-offs. Which in this case the big one is the better overall sound quality of your Mofi compared to the (possibly) more accurate EQ of the cheaper lower quality stage.

Again this is not my area. But it may well be that you find the difference is a lot of trouble for not much more than the satisfaction of having solved a technical problem and "done it right".

Thanks. I’ve read that some recommend just using the standard riaa phono pre and forget it. Most 50’s 78’s by the major labels are RIAA anyway ( from what I’ve read). I’ll probably start with the mofi and go from there

That's what I would do.

A quick search turns up this
http://pspatialaudio.com/record_characters.htm
which is about what I remember.

The main reason I looked that up was curious attraction I have for the even older phonograph 78s. No RIAA there! For all their many sonic shortcomings I nevertheless somehow find them utterly captivating.

I don't know anything about 78s, but I do know that the Parks Puffin has multiple EQ settings and you can customize your own as well and it's only $450.  I have one and have been really happy with it.  Might be worth checking out.  

A brief internet search suggests that equalization for 78 rpm records made prior to about 1950 is a veritable can of worms.  I was surprised, because I might have guessed that equalization was not used back then.  If you're going to use a dedicated 78 stage with no equalization, be prepared for tonal imbalance.  As to the question about grounding.  There's no harm in what you propose to do and possibly also no benefit.  Sometimes you will reduce hum by NOT grounding the tonearm or turntable to the preamp. If grounding to the MoFi doesn't work, then try grounding to the 78 stage.  The only risk is loud hum, either way. In my book, leaving the ground wire on the MoFi while you listen to 78s using the dedicated stage is akin to no grounding.

Look for Gold Note PH-10 phono stage and you will find alternative setting for RIAA. You can choose one of three standard EQ curves (RIAA, DECCA-LONDON, AMERICAN COLUMBIA), all with optional “Enhanced” function.

for an excellent phono stage that's reasonably priced look at the IfI Iphono2 I used one for a year and its surprisingly good for less then $500, it has an impressive loading gain settings and RIAA, DECCA and one other I cannot  recall. Its really good for the money and a 3rd the cost of the Gold Note and not that far off from it in sound. I went from the Ifi Iphono2 to the Gold Note ph10 by the way.

glen