Improving existing setup, where to start?

I want to hear those speakers!!!! Live near me? Central NJ.

I suggest you think long, future flexibility, let that influence your decisions now. Especially if you might add/go back to MC cartridge. And you may change to a separate dedicated 2 channel system in the future.

I just went thru a few TT progressions piecemeal, as follows

1. longer arm, thus needed a larger deck/plinth
2. direct drive quartz locked for instant/constant speed
3. mono cartridge, definitely better as I learned here
4. two arms on the larger deck/plinth, 1 mono ready to go, the long arm stereo,
5. how to switch tonearm inputs instantly in listening session? Didn’t even think about it, I got lucky, my preamp has phono 1/MM and phono 2/MM (you now have a single MM phono input it seems)
6. MC Cartridge (my first one, finally), now how to boost up to MM strength?
7. MC Phono Preamp OR Step Up Transformer (SUT). As I love the sound of my existing tube phono, I went SUT.
8. SUT for a specific cartridge, single in/out, specific MC load, OR, flexibility for the future? I searched extensively, I went for 3 selectable tonearm inputs, PASS for MM, 4 optional MC loads, front switches, risked vintage to save money and I love to keep great vintage stuff going

https://www.ebay.com/itm/Fidelity-research-FR-FRT-4-Toroidal-Transformer-In-Excellent-Condition/3336...

9. You might not think your Marantz phono is wonderful, you could buy a separate Phono stage, you mentioned not too pricey, I tried this $300. one. Keep it or return it. It has MM and MC, but only one MC loading choice 100 ohms which I found too limiting.

https://www.cambridgeaudio.com/usa/en/products/hi-fi/phono-preamp/duo

10. Now, I’m going to squeeze a 3rd tonearm on the left side of my 2 arm plinth, for ready to go Mono/MM (replaceable stylus)/MC (using MM will reduce wear on non-replaceable MC). I will find a compact arm with surface mounted arm plate, a simple hole thru the 70mm deck, a 9" will fit
It’s big for 2 arms, but that will be fairly compact for 3 arms with dust cover tall enough for more arms to fit.

EASY, because I went for future flexibility, my SUT has 3 inputs for 3 arms (MM or MC), and the preamp has two MM. Not luck this time, flexibility was key in my selection.

My point is, had I thought it thru all together before I started??? I’m very happy with the result, but feel lucky that it all worked out. I had a whole lotta help here. see the last photo here

https://www.ebay.com/itm/George-Harrison/133534402519

Wow, thanks for all of that great information. That rig looks intense! I'm just beginning to ease back into things, you're like a mad scientist : ) 
For now, I'll have to have a hybrid system with home theater. Someday down the road I'll start up a dedicated 2 channel system and begin my decent into madness once again. 

I've had the Gallo's for maybe 14 years now, still going strong. Unfortunately I'm far away, Omaha, NE. It's too bad they no longer make them. I believe the cost of the aluminum stem became prohibitive. 

Baby steps...

Replace Red stylus with Blue stylus ($160 if you shop around and you then have a backup/Red stylus - a backup is always good to have on hand).

Listen for a few hundred hours, and if not satisfied look into a different outboard phono preamp.

Also, check/redo cartridge alignment/setup if you are capable of such.

If not, then learn how to DIY.

DeKay

I’m not familiar with your amplifier but one of the Rogue tube integrated amps has a built in phono stage. I’m somewhat skeptical about replacing the Marantz based on your budget. My understanding is that phono amps really begin to stand out at around the $2,300.00 mark. So if it were me and I had to be fiscally conservative, I’d first buy the best cartridge I could afford.
As far as nice stand alone phono amps, there are plenty on the used market. For whatever reason, good tube phono amps tend to be a good deal more expensive than solid state. I have an ASR Mini Basis Exclusive and I believe it’s very good for the money and it offers the tone of a tube amp with the bass and transients of a solid state. I need a better tonearm and then a better mono cartridge and I’ll have for the most part completed my analog setup.
If you’re satisfied with the sound after you upgrade the cartridge, then relax. It’s all about the music. I’m saying this as I’m spinning a 1954 Haydn Society box set of vinyl remastered from 1938 recordings.

Thank you guys for the replies.

DeKay, I'm almost certain now that this is a great starting point. Seems very easy to swap the Blue stylus out and then ensure the cart is perfectly setup. 

The damn thing came with a Goldring Eroica high output moving coil and I was using a Jolida tube driven preamp, sounded amazing and I've chased that sound ever since. I think one of my kids messed with the table and broke the stylus. At the time, I had no idea I could just replace the stylus so I just threw a cheap cart on it and stopped using it. 

Anyway, Blue stylus and proper setup followed by phono amp. Perfect, thanks!

Yes mani schiit is  very very good, I like the speed and the explosiveness of this phono preamp, it match well will ortofon blue mm...