Is a separate phono pre really necessary?

any phono eq that takes low output mc, you are running thru it's internal SUT anyway. 

my SUT has 3 tonearm inputs, PASS for MM, and 4 optional transformer windings: 4 optional x factors and the 'resultant' impedance (determined by x factor squared) that will be 'shown' to a MM phono input.

Fidelity Research FR-4

https://www.vinylengine.com/library/fidelity-research/frt-4.shtml

I go to my beloved Tube Phono MM input. in my mx110z.

You might consider a tube preamp for everything, including at least MM Phono. then use an external SUT, or a Tube Phono EQ for both MC and MM with many configurations to Line Level in your amp.

ANYTHING involving Phono, have return option, it's tricky what works for you.

One of the Primary reasons to use a SUT is to maintain the sound characteristic of your existing MM Phono Stage. I love my McIntosh mx110z's MM phono stage, thus I went for a SUT for my MC cartridge, boost enough, then into/thru the mx110z's MM Phono EQ, maintaining it's tube sound characteristics.

If you do not like the sound of a phono stage, like I disliked my McIntosh SS C28 Preamp's phono, then it is better to go to a separate phono stage up to line level, use the preamp for volume/balance/tone/mode as needed.

I actually found a $14. MM Phono that sounded darn good from Pyle. And, before I gave it to a friend, I used the optional built-in phono eq inside the AT120 tt over the McIntosh C28.

PASS is a desireable feature on a SUT so you can change headshells or different tonearms from MC gain to MM PASS, same wires to the preamp.

I looked up your Preamp review on Absolute Sound.

Great collection of remote controlled features, including balance in very small steps.

Take any reviewer as you will, he gave High praise, except the phono stage, excerpt:

"Turning to the phonostage performance, overall imaging was stable and transients retained their spontaneity. There was solid underlying continuousness across the soundstage, as well. However, I heard a lighter energy and cooler cast in familiar recordings. The sound wasn’t quite as richly varnished compared with other sources I’d input through the RP-5. One instance would be the new Impex LP remastering of Jennifer Warnes’ Famous Blue Raincoat. During “Song For Bernadette,” Warnes’ vocals seemed a little less rich and colorful, and the airy buoyancy of her head-tone was a dash drier. I have to confess the phonostage was a little bit disappointing given the overwhelmingly positive nature of the experience up until that point. However, to be fair, I was running the phono at maximum gain for the benefit of the Palo Santos Celebration moving coil (0.5mV), and though it was reasonably quiet for this class the RP-5 phono section couldn’t match the seriously quiet Parasound JC3+, proving once again that I’m spoiled, and that it’s hard to beat a premium outboard phonostage for isolation. For a built-in phono with this level of optimization, it still represents good value."

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1st: are you certain you have the 3 configurable internal settings correct for your cartridge? Your preamp has Separate internal switches for capacitance; resistance; gain settings, that’s awesome, IF correctly set.

2nd: currently, are your LP’s involving, better than CD or streaming, .? If yes, stay happy. If not, then yes, a separate phono stage is needed, not a SUT, a full phono stage to go thru a line level input.

I would advise having full return option and try/return/keep a separate one until you find one you love. It ain’t easy.