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.