I've now had the pleasure of having both amps in my YG Hailey 2 -based system.
I don't feel there is a generic winner or loser, although the JRDG drives the Haileys much better. The Luxman has more texture, but a smaller soundstage with a slightly shelved top end. The JRDG excels in microdynamics and has better bass than the Luxman with really silky, sweet highs. The Luxman is more midrange focused, while the JRDG is more top down I'd say at this point. Neither are bright of course. The 625 does lack some low midrange/upper bass weight - we are going to play with some speaker positioning today and see if that changes things. The cello for instance isn't quite fleshed out enough in classical music.
I've also had my trusty Ampzillas in session with these big boys and they aren't embarrassed. They aren't as transparent as either, but are very musical, dynamic, and perhaps more even top to bottom on the Haileys. The Zillas lack some decay that the Rowland provides and I feel would pair better with a tube preamp than my Music First.
Now you guys understand what I've been doing in quarantine. I've been trying to find an amp that doesn't cost as much as a D'agostino S250, but will provide similar enjoyment.

opcorn: