One has to generalise as both produce a range of product. The Plinius is a transistor design and sounds like it - a little crisp, slightly wiry in the upper mids, and slight hard grain in the treble. If the Perreaux is not Mosfet (which I think it is) then it certainly sounds like it - typical Mosfet haze, softer than the Plinius, and easier on the ear, but a bit flat with a soft grain over everything. The superior PRAT of the Plinius makes it a "no contest" for me. Others find the softer, gentler, yet powerful sound of the Perreaux more to their taste.