How to remove harshness from my digital gear

Before giving up on the Classe transport and the Moon DAC3 (is that the right model number, btw? I couldn't find any info on it), if you already haven't I would suggest that you try all three of the Classe's outputs (AES/EBU, coaxial S/PDIF, and optical S/PDIF) if the DAC3 can accept them. Also, I would suggest that for the AES/EBU and coaxial S/PDIF connections you try cable lengths that are either about 1.5 meters long, or that are very short if that is practicable (i.e., about 8 inches or less). See this paper.

IMO there is no such thing as a neutral digital cable, because the sonic effects of a digital cable will be highly dependent on interactions between its technical characteristics and the technical characteristics of the particular components it is connecting. And many of the key characteristics that are involved are usually unspecified and unpredictable.

Regards,
-- Al

Robsker, good comments by Steve, of course. I would add that if you already haven't things I think you should do early on (in addition to his item 1) would be:

(a)Verifying that the hum is in fact due to a ground loop, rather than being generated internally within an individual component.

(b)If it is in fact being caused by a ground loop, identifying which two interconnected components (together with their AC power wiring) comprise the loop.

Both of those things can be accomplished by a process of selectively disconnecting components from the system, and TEMPORARILY using cheater plugs (3-prong to 2-prong adapters) on the power plugs of suspected components.

If you eventually determine that the problem is due to a ground loop between two specific interconnected components, inserting a quality transformer/isolator between them, as he indicated, should resolve the problem.

BTW, and this pertains to the OP, ground loop-related noise can be present on digital as well as analog signals (assuming that the digital interconnection is electrical and not optical). In the case of a digital signal it will not manifest itself as hum, but can be a significant contributor to jitter, and therefore to harshness. Differences in the type and length of the digital cable that is involved can make a difference in the severity of that effect, although with little or no predictability.

Regards,
-- Al

Hi Robsker,

There have been a number of debates here about using cheater plugs as permanent solutions to hum problems, such as in this thread. As might be expected, opinions are divided. Some people do just that, while others argue fervently that it is a serious safety risk.

I believe that the following comment I made in that thread is indisputable, assuming that the equipment is in good physical condition:

If a fault were to develop in [a component] that shorted the AC line voltage to the [component's] chassis, there are various scenarios in which that could result in both a shock hazard and a fire hazard. How great are those risks? Very, very small. But it cannot be said that they are zero.

Regards,
-- Al