DAC drops out when Furnace starts or stops. HELP

OK, so I started by changing the digital cable (it was the easiest). I had been using an Audio Envy cable that I really like. Had it about one month. After inserting it into the system I had an occasional drop out but didn't think a lot about it. However as the cold nights came I started having more and more drop outs. Which lead me to tracking down the cause. Thus I discovered that it was the furnace and water heater making the disruption. Prior to the cold snap, it was only the turning on and off of the water heater that caused the drop out. But now with the furnace in the mix the drop out rate was increased signifigantally.
I replaced the AE cable with a Grover Huffman digital cable and last night experienced no drop outs.
The AE cable is only one meter while the GH cable is 1 1/2M.
Is it the length of the cable that could be the culprit or is it the design/construction differences?
Either way, thanks for the suggestions to get the gremlins out. I will also look into the service panel today to check the wiring as to which leg of the mains might be in common.

Check the polarity of your kablivit pin.

The AE cable is only one meter while the GH cable is 1 1/2M.
Is it the length of the cable that could be the culprit or is it the design/construction differences?
10-09-15: Jadedavid

Hopefully someone like Al, (Almarg), will chime in.

As for the AC power side of the equation when the furnace or hot water is turning on or off a transient spike is being sent out on the AC mains. Just guessing the transient causes a quick brief problem with the DAC or maybe even the transport. For some reason the AE digital cable is not capable of maintaining a good digital lock between the transport and the DAC. It's like the AE digital cable was just on the edge of maintaining the digital lock between the transport and the DAC before the transient spike event would happen causing the drop out.

Either way, thanks for the suggestions to get the gremlins out. I will also look into the service panel today to check the wiring as to which leg of the mains might be in common.
10-09-15: Jadedavid

You never said if the furnace or hot water heater are gas or electric.
If electric my guess is they are fed by single phase 240Vac.

Length of the cable might or might not add to the problem.
Longer cable allows to avoid first reflection adding/modifying shape of original transition (many factors involved). You GH cable might work better because of length or because of better characteristic impedance match. Most likely it is just a better shielding.

Good call on the cable, Jim (Jea48). I would not have guessed that. And your explanation sounds very plausible. I agree with Kijanki's comments as well.

Jadedavid, the reason that a length of 1.5 meters is often recommended for digital cables is further explained in this paper. It relates to the potential effects on jitter (short term fluctuations) in the timing of D/A conversion, that may result from the inevitably less than perfect impedance matches between the cable and the components that are being connected.

As Kijanki indicated, though, and as can be inferred from the paper, many system dependent variables factor into the likelihood of that length being optimal. A notable one being the risetimes and falltimes of the signal that is sent into the cable (i.e., the amount of time for the signal to transition between its lower and higher voltage states, and vice versa), which are generally unspecified and unknown. So while 1.5 meters may generally stand a greater chance of being optimal than 1 meter, that will not always be the case.

All of that relates to sound quality, though, and usually not to the kind of problem you have encountered. But I wouldn't be surprised if the characteristics of the shield relate to it, as Kijanki indicated. Given that two different appliances cause similar symptoms, though, my guess is that it is not differences in shielding against RFI pickup that are involved, but rather effects of the shield or other signal return conductor in the cable on a ground loop issue that may be occurring between the two components. A ground loop issue conceivably resulting in the marginal lock Jim referred to.

An interesting experiment, therefore, might be to temporarily put a cheater plug (a 3-prong to 2-prong adapter, with the safety ground connection not connected), on the power plug of either the DAC or the component that is providing the signal to it. That would break any ground loops between the two components. Then see if the problem still occurs with the shorter cable.

Regards,
-- Al