I have my digital cable going through my Sony STR-D986 receiver through a digital coax cable made by acoustic research. When a large appliance in my house kicks on like, central air or a washing machine,the digital audio signal is interupted for a second or two. Does not happen when it is hooked up via analog connections. Could this be the audio coax cable or the receiver???
Heck no!!! What you are experiencing is called a brown out. Its a small brown out but, still can be very damaging. The reason is that thoese large appliances are drawing so much juice that the other appliances cant get eough (ie your reciever, and cable box). The easiest way to fix this is with a device called a UPS, or a uninteruntable power supply. What this is, is a box with a big battery in it. You plug your surge suppresor into this, and this into the wall. This way, when the power dips down, or even completly goes out, all your equipment is still running. Now, in the case of a power outage, this will keep it running for 15, 20m tops, but, in the case of a brown out, when it is still recieving some power, the UPS will give it the extra power it needs. As well as the ups, you should probably get a better surge supressor. Make sure you get something that has a power conditioner. THis will take that eregulatr power, and clean it. Trust me, you will notice a massive improvment, and this will only cost you about $300 ($100 surge supresson/power conditioner, $200 small usp)