Why not use speakers with a wireless bluetooth connection? That can be done with most sound sources.

Bluetooth speakers require a power cord. I don't have an outlet on the back of the property. Plus I wanted stereo sound , 2 speakers. And they aren't that great usually.

I've already spent 100 something on the speaker wire...just need to know best way to bury.

Yes you can use direct burial speaker cable suitable for wet locations. It has the same jacket as landscape wire does. However, it can get cut by gardeners and such so it would be a good idea to put it in PVC to protect it. As long as your setup is low voltage there is no required depth like there is for line voltage electrical. However, it is not a bad idea to follow those same guidelines which vary between 12in and 24in below the ground depending on what they go under. Typically if you are retrofitting this wiring you would mount a surface mount PVC box over the penetration of the speaker wire from inside to outside the house and then seal the PVC box with silicon to make it water tight. Then run a 1/2" to 3/4" Sched 4 PVC pipe to the ground to whatever depth you decide and use a combination of 90 degree, 45 degree and 10 degree offset parts to get where you need to for the speakers. Pop up the conduit above grade again close to the speaker location and add another box to finish the conduit. Cover it with an outdoor PVC blank plate and gasket to keep splices dry and then splice that incoming speaker wire with the wire from the speaker. You can also just run the speaker wire directly to the outdoor speaker without a box-- its up to you. Just don't leave any conduits facing up that can collect water-- you don't want your cables sitting in water if you can help it.

Thanks for response technospeak.

At what wattage or level does is the line considered no longer low voltage? For example if I get a small 2 channel amp to run the speakers, it would be considered low voltage....but if its a hi current hi wattage amp....does it then change to a need for a necessary depth? or is high voltage reserved for other types of equipment for power like landscape lighting or something else?

You definitely exceeded my intelligence when you wrote about the boxes and blank plates and gaskets. I will need to google what a setup as you mentioned looks like. I can visuallize pvc running under ground but I'm unsure what the other entry into ground, boxes, and plates you mention. I currently have rock speakers but I'm now contemplating speakers to be mounted on my back fence. I think I no longer want equipment on the ground taking up walking area or on grass. I was thinking of converting to landscaping and so the rock speakers seemed like a good choice, but between growth of plants or if I never plant anything, speakers off the ground might be a better option for versatility in future changes. Unless I plant a tree in front of them lol.

I intend to start digging this upcoming week. I had some medical issues which has caused a postponement of some things. I have to make sure I don't accidently cut into spectrum wires or att wires while I'm digging the trench.

Thanks again technospeak.

If you have some customer images or example of a final product or even the install process showing the pieces you mention, the conduit, boxes, etc... that would be greatly appreciated. I'll be googling as best i can what you said before I buy some pvc or anything else.

Well you can go by a few different definitions. From a C7 license standpoint (which is one of the licenses we have), 91 Volts and below is Low Voltage. The NEC has a couple of references to low voltage but one many hold to to be true is less than 50 volts. So technically if you were going to get this installation looked at by an inspector anything over this would necessitate the conduit depth to be the same as if you were running line voltage. The inspector would look at the specs of the amplifier you are connecting these speakers to and make his judgement on required conduit depth based on that. However, we have yet to see anyone call for an inspection on installs like this. Even when we work on residential new construction and the jobs calls for landscape speakers, inspectors have never looked at this when onsite and passed the installation without issue. Commercial is a different story of course but you weren't asking about that. Just make sure you get speaker wire that is rated for direct burial at wet locations and keep splices off the ground, protected and inside waterproof wirenuts. My personal favorite for landscape speakers is these: http://www.sonance.com/outdoor/sonarray. We will take some pics and post for the next install we do like this.