The Ares Magnum internally uses a blue-label CineMag 1254 SUT (step-up trasnformer) for its MC modes - this is very similar to the Bob’s Devices "Sky" step-up transformers, which are excellent. It provides exceptionally high gain at 20x and 40x ratios, with exceptionally low noise (** unless you have a grounding / wiring issue). This makes for one of the best MC "pre-preamplifier" stages you can find built-in, at any price point.
The Ares is also unique in its loading options, which allow it to match nicely to "oddball" LOMCs that otherwise cause severe loading issues with SUTs into 47K MM inputs. The most common example of these is the Benz Ruby / Gullwing / LPS, with their non-magnetic ruby coil former (which is the reason they’re a tough mate to SUTs loaded at 47K - the ruby former gives up a LOT of signal output level for any given number of coil turns).
Even though tubes have more noise than good SS implementations, they’re only handling the MM stage/levels here, which keeps things in check. So in short - low, low LOMCs (even 0.18mV) are generally no problem for the Ares’ architecture. Now sometimes, some of the Ares units in the past have had minor wiring / grounding issues that can cause hum noise, but hopefully these have been more consistently addressed in the II. If not, a return to the factory can usually sort it out (Rogue service & support is exceptional).
One warning - the Ares’s tube MM stage is not a tubey / "romantic" sounding one. It sounds more clean & neutral. So if you’re expecting extra tube warmth, you won’t get much of it here stock. But you can get a bit more of that by tube rolling (e.g. vintage Mullards). It’s still never going to be as sweet sounding as say a VAC phono stage, or a Hagerman Trumpet. But then again, the warm & meaty CineMag SUT is very good in combination with clean & neutral MM.
Also: don’t confuse the Ares Magnum and II Magnum with the original Ares non-Magnum. The latter used red-label CineMag 3440A transformers, which are pure garbage compared to the Blue 1254. The Red 3440A has much lower gain and also sounds much worse at any gain.