Luxman, Plinius, Sugden are all below Accuphase. I don’t like the sound of Pass equipment.
It’s all subjective, and the speakers that are matched to the amp will play a part too. No right or wrong. From the list, I’ve owned Plinius Class A power amp and currently own a Class A Luxman. I’ve not heard the Accuphase but read that it has a warmer midrange glow than the Luxman.
Between Plinius and Luxman, I would say the Plinius sound more like a Class A to me, warmer midrange and fuller bass. The Class A Luxman has a rather neutral presentation although it sounds slightly warm. I find the detail and refinement of the Luxman to be a step higher than the Plinius. With the Plinius, some of the details may be missing, toned down or smeared. The Luxman is a more transparent amp with higher levels of clarity and detail in comparison to the Plinius. The leading edge of notes are all sharp, defined and pin-point with good clarity. With the Plinius it sounds a bit smeared. If one prefers a punchy, full and thick bass, the Plinius will be better but it doesn’t have the agility and refinement of the Luxman. The bass of the Luxman is leaner but with better clarity and detail when compared to the Plinius.
In my system, I wouldn’t want something that sounds warmer than the Luxman so I presume I won’t like the Accuphase which is generally regarded to have a warmer sound than the Luxman