I've always considered Pass Lab to be one of the best solid state amp designer in the industry, having owned and listened to many of their XA and X models, I'd have to say the D'Agostino is on the same level. Never had extensive experience with any of the other amps mentioned beside listening at RMAF so I won't compare.
For a high powered amp it is very musical, it is on the warm side of neutral but not as warm as the Vac Phi 200 I previously owned and closer to the modified Audio Valve Challenger I still own using KT120.
Bass is tight and powerful when the music calls for it but with most material it is well textured and doesn't reveal itself as a high power amp. Never heard any hardening of the highs as the Absolute Sound review suggests, but how can they say an amp at this price is complete when there are so many much more expensive including other models from D'Agostino. Soundstage is noticeably deep, the width is consistent with other SS amp I've heard. Detail is excellent!
Overall, it is musical, refined, and and I'm a happy owner. This amp does require an extended warm up time similar to tubes especially if you don't listen often like I do.
For preamp, I would go VAC just because I'm currently using a tube pre and it's working for me.