I actually compared the two back in the day. They are both excellent amps, but the Jeff Rowland ended up dull and dark in comparison. The Plinius is cleaner and has more detail and definition to the midrange. The Plinius has a tighter bass with good slam, and a much more open top end.
I ended up buying the Plinius SA-102 and have owned it ever sense. The only amp I have heard that I would replace it with is the Plinius SA-103, but I can't afford to upgrade.
I ended up buying the Plinius SA-102 and have owned it ever sense. The only amp I have heard that I would replace it with is the Plinius SA-103, but I can't afford to upgrade.