Which component to upgrade 1st ?

I'll put in a counterpoint for consideration. Consider isolation, power cords and interconnects. Depending on what you have and when the last time was that you truly evaluated these elements, it may be the biggest upgrade and change you will experience. Good mechanics is essential (as well has room acoustics) to optimizing your listening experience.

For example, I just upgraded my rack and turntable isolation to Core Audio and Minus K from Finite Elemente and Stillpoints Ultras. Earth shattering change. I'm serious--way beyond what I expected. And I expected a lot (even with a system that was pretty darn good going into it).

Give it some thought.

You've got to make spending count.  Must be a case for choosing between analogue and digital sources.  Why spend money on two competing systems?

Meanwhile some are putting money into power cords instead of active components.

I recently had the same dilemma, but took some sound advice: change sources, amps and speakers to change the flavour / character of your system; change DACs, pre-amps and cables to fine-tune it. So I recently bought a 2nd-hand Sonnet Morpheus DAC and a demo Primaluna Evo 400. Kept my Audiosolutions speakers, my Auralic Aries source, and my Ayon pre-amp, but I'm selling both my previous $5,000 (US) DAC and some $15,000 (US) mono-blocks. Couldn't be happier. You need to sort out the weak links in your system and do lots of research, but the answer doesn't always mean spending more, as there are some real audio 'pearls' out there and technology keeps moving on. In that regard, I would definitely think about MQA - despite what its many critics might say. I've dropped Quobuz and focused on Tidal because of it.   

@littlebrownkiwi01 …Change the flavor/character by changing the speakers/amp

…fine tune with DAC, preamp, and cables

Interesting, I hadn’t heard anything like that before. I keep wanting to put the preamp in with the speakers and amp. But… yeah… OK… it’s a generality… it makes sense. It could be useful for your first system or for making a major change in character of an existing system.

About 15 years ago I wanted to make a major change from planar speakers to a more natural coherent sound. I have always had a great preamp… I changed the speakers (to Sonus Faber) and then the biggest of the other changes was moving to a tube amp.

A rule of thumb that can be useful. Thanks for sharing.

The ML Vantage have a powered woofer. So the panel is pretty much the only thing that presents a challenge to the amp. However, I think you’re fine with the ARC amp driving the MLs. I had the ML Montis and used Rogue ST-100 tube amp mostly in triode mode which puts out about 60-65w/ch. I also used Pass XA-30.8 with the MLs and it rarely moved out of pure Class A operation.

Even though the Qutest is a great DAC, IMO upgrading the DAC will be the biggest impact in your system especially if you switch to running all XLRs with the ARC gear. The Weiss 501 DAC should be great and will replace both the Node and the Qutest.
I would then tackle the preamp next and would look into something like ARC Ref5/se. Stay with the ARC for your preamp for synergy, sonics and a piece of mind.

By the time you’re done with either or both upgrades, you’ll sit down for a listen one day and realize that your speakers are not on the level with the rest of your gear. 😀

You mentioned you like warm sound…may be look into Harbeths when you get around to the speakers.