Well it will be a good long while before I can give an honest feeling on sound quality because SimAudio states it takes about 300 hours to break it in

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Initial out of box impressions. The Moon is larger and a lot heavier. It wreaks of quality. The size does make it harder to place, like it barely fits on the stand I use for headphone amps. I like that it has a remote. I like that the balanced outputs are under the slide. Very classy. I also love the volume control. The Bryson got too loud too quickly on the control to the point that I would set the DAC on variable output to turn it down to be able to control better.
One other huge difference is that the SimAudio has a lot more power than the Bryston. The Bryston is rated at 2 W at 32 Ω and the SimAudio is rated at 8 W at 50 Ω. The higher the impedance the lower the power rating, for example the Moon is rated at 1.33 W @ 300 Ω and 667 mW @ 600 Ω.
The SimAudio volume control is a thing of beauty. Smooth, extreme fine tuning. Like 530 steps or something like that. A ton more control! All included accessories are of very high quality.
Sound quality is great so far, it is excellent but too early to say. Seems smooth, on the warm side. I would call it almost tube like. Very very quite though, no noise what so ever.
The feel of the amp is far higher then the Bryston, but I also remember the Bryston being very impressive.