If you had $12k / £10k to upgrade your analogue front-end...

With what you have maybe start by simply trying another cartridge with enough output to mate with your current Moon?

Based upon reviews the Performance V2 can easily be bettered (the Ace/Concept have stellar reviews).

If this does it then good (you could alway add a step-up/MC later or go with the Moon separates) and there is no downside if you choose the higher output cartridge wisely.

See what your current deck is capable of before moving on.

Take a look (reviews) at the Nagaoka MP-500.

DeKay

Since you're obviously in the UK, I would absolutely demo two or three Nottingham Analogue (Dais or better).

@whart  is right - it is very difficult to demo the analogue front end, because it's not always clear what you are hearing (cartridge, arm, table, and especially how well they have been set up, not to mention phono) but, and it's a big but, sometimes you get lucky and find a combination that's head and shoulders above the competition. That's how I ended up with Nottingham.

How good was it? Until I built my DIY air bearing table, it was the best I had heard at sane prices. But you can definitely improve on the arm, at least you can if those of 20 years ago are still representative. The most important things in an arm are rigidity, low resonance, and adjustability.

Remember, no setup without adjustability, preferably adjustability on the fly.

Pair that with a Dais and then you have a table upon which even a big Koetsu is not wasted. Then you can ask to home demo a phono stage to suit.

At least, that is how I would proceed. YMMV. Good luck!

@cainullah Is the internal phono stage good - I think so. I used to own McIntosh C2600 with an internal tube phono stage and preferred the 390. 
 

I don’t feel the need to upgrade the phono stage at this point - I appreciate the simplicity. 

reading some of the comments, I really started to wonder how much difference the phono stage will make. My understanding from what I am reading is that it yields the littlest gain in the chain (say: 5K on a phone stage, 5K on a TT vs. 2K phono stage, 8K TT - the latter being a much better allocation)

But that seems the opposite to what commenters say here.

Then, I am also clueless about the best allocation of the TT components and I don’t care as I have no plans to mess with them. Rega’s choices are fine for me (but it seems to be arm/cartridge/plinth, platter?)

I think what I am trying to say: it's not an Olympic event where winning is everything and pouring millions into Michael Phelps' diet will pay off by that .1 seconds at the end.

It's just a bunch of decent components that will (should) do their part for 1000s and not 10s of 1000s (unless you have a giant concert hall to work with).

I guess that goes against 98% of what's being argued here :)