It was not a direct comparison of the Ref 2SE and the XP25, but early last year we did a phono shootout involving the Ref 2SE and the dual Xono, among other phonos. As the name implies, the dual Xono setup utilized 2 sets of Xono, but used only a single channel in each set. Every area, especially the effortless presentation, got improved considerably compared to a single set of Xono. The cartridge used was an Ortofon SPU, which had a low output of about 0.2mv.
To me that was a tie between the Ref 2SE and dual Xono. The Ref 2SE had the traditional ARC characters, high resolution and awesome dynamics. But I also felt it was slightly on the cool side of neutral, and lacks some of the tube warmth, as well as body and bass authority, when compared to the Aesthetix IO Eclipse.
The dual Xono, while also having a dark background and awesome dynamics, sounded slightly softer than the Ref 2SE. To me, the Xono still had a touch of the SS sound, and also slightly on the cool side of neutral, so it may not be the cup of tea for someone who prefers the classic tube sound!