Would the Mogami Gold be a significant upgrade from the Blue Jeans cables, at least at this stage until my system is complete?If the Blue Jeans cables are the ones that utilize Canare L-4E6S, I would not expect much if any difference.
If they are the ones that utilize Belden 1800F, the Mogami has significantly higher capacitance but significantly better noise rejection. That would include rejection of noise at ultrasonic and RF frequencies which may not be directly audible as noise, but may have audible consequences due to intermodulation effects. Although the balanced input circuits of the amplifier presumably should cancel most such noise anyway.
The higher capacitance of the Mogami, compared to the Belden 1800F, may result in a very slightly more relaxed upper treble, if driven by the 500 ohm or so output impedances of the Onkyo and the DSPre. The magnitude of the difference will increase in proportion to the length of the cables.
Other differences, if any, are probably not predictable.
Regards,
-- Al