I went from a 500 to a 588, then onto mostly streaming with a G98 as a transport for the rare time I wanted to listen to discs. I was using DSPs with all of these, but heard a clear difference going from the 500 to the 588. I preferred the 588, but could see how others would like the 500- they were both excellent. This was all using the digital output, so there can indeed be differences among transports.

I would expect that the Ultra DAC should really work some magic on the incoming digital stream, so it may not make much difference.

Theater: 861v4_LPS, 818v3, HD621, Oppo 203, Lumagen Pro, DSP8000SE, DSP5500C, SW1600x2, DSP5500, Epson 6040UB, PS4
Living room: 861v4_LPS, HD621, DSP8000SE, DSP5200C, Oppo 203, Lumagen 2143, 818v3, Sooloos/MC600 Bluesound Node
Bedroom: M80
office: G68D, DSP6000
Garage: DSP5000
Storage: M33s, DSP33s, DSP5k, 501, 518, M1500, G98DH, SW1600