I use and Apex Pinnacle as a preamp and headphone amp.
Actually, I just replaced the Sophias which I liked for their even-handed sound with fine low bass and highs, but, when I put in the (new in box) Psvanes, I immediate liked them much better, with the vocals just so more realistic and a more natural image boundaries, the opposite of paper cutouts.
And the sound staging was better, with a deeper field and an easier time finding centered images.