Instruction: Extract information from the supporting document to answer the given question.

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Question: I have a 5.1 wired setup already. Is there any reason this couldn't be used to power the other two speakers for 7.1?
Document: The Rocketfish satellite receiver is nice looking and easily concealable, as is the sender, and the product does what it says it will.Unfortunately if you're running 7.1, you will need two of the device, as it only accommodates 1 set of speakers per unit.The only other product like the Rocketfish I could find was a Bose Wireless Rear Speaker Kit, and it costs $250. I haven't used the Bose kit, but for over double the price, I'm willing to just stick with my Rocketfish.One thing to note, due to the lack of power the satellite receiver provides (only 20 watts per channel), it does not have enough power to run Dolby True HD or DTS HD Master Audio, so if you can afford to sacrifice the uncompressed audio formats, then this product will suit you just fine.Pick this one up if running wires is not a viable option for you.
It also has a compartment underneath for storing any extra length of power cable. The included wiring seemed pretty cheap, so I used 14-gauge copper wire, but it was a tight squeeze in the terminals on the units.Once everything was wired and plugged in, I didn't even have to press the "connect" buttons - the units synced immediately and I was good to go... but there were two annoyances. First, distracting white noise/static from the speakers. Using the receiving unit's physical volume knob I could eliminate the static, but then the sound was too quiet.
I am very pleased with this unit after using it for two weeks. It worked exactly as advertised and seems to be working flawlessly. I'm using it with my rear surround speakers in my 5.1 surround setup. My living room is on the small side and I would estimate that my TV and front speakers are about 15 feet from my rear speakers. I have no Wi-Fi or portable phone interference whatsoever but the nearest Wi-Fi router is about 40 feet away and these units are only separated by about 15 feet.I had no problem balancing the surround sound on my Yamaha high-powered receiver after setting the volume control on this device's amplifier to full.
I got this with the intention to pipe the surround sound to my rear speakers without running speaker wire across my living room. For the price, this is a fairly decent setup, with little interference. I also have a 802.11g home network, plus perhaps several other 802.11 networks from neighbouring apartments. For the most part, the sound is pretty good and clear.The only reason I am not giving this 5 stars is because I sometimes get popping noises from the rear speakers. Although this is occurs only once in a while, it is mildly annoying, and I get the sound even when the source is switched off.
The product is a quality item. I  bought it two years ago as an open box item at BB. 500 sqft family room. Wi-fi in the house connected to wii 360, ps3, Samsung LCD and pc, cordless phones, works great and is easy to set up and u just plug it into your  speaker output of your amp.Specific con to my set up and amp: I have my receiving box hidden behind my couch and connected to my Onkyo amp with "2 -zone" capability as "rear speakers" in a 5.1 set up.
I purchased this kit with the intent to use it not in a surround sound system but to pipe music to two speakers in another room, so that I can play music in multiple rooms. I set it up so that the Rocketfish sender is connected to my Audio-Video receiver unit's output for front stereo speakers (while the front stereo speakers are also connected to the same output). The Rocketfish receiver was setup in the other room and I hooked it up to two other speakers. And it works great! I can play music through my audio-video receiver and listen to it while I'm in either room.My audio-video receiver can also be used to play surround sound but like I said I'm not using the Rocketfish kit for playing surround sound in the same room, but to play stereo sound in different rooms.
I bought this because my wife did not want wires running across the living room to the rear surround speakers. They work as advertised. However, I had two unanticipated problems:1) The power is very low. Even when they are set on maximum, we can barely hear them. There seems to be a real limit to the power they can put out.2) When the "transmitter", no longer receives a signal, the rear speakers put out a very loud hum. Thus, when my wife turns power off our Pioneer A/V Receiver so that the Rocketfish no longer gets a signal, then it generates a loud hum.
I have used this for years because wires are not options. I don't hear any background noise or pops. It never broke down as other reviewers claim. Very very seldom, the connection is lost during intensive audio moments of movies. Like loud crashes but that is almost never and you just hit the reset button. By the time you sit down they are already active again. That has happened to me like 3 times in about 3 years. Love it! Wired would probably be better but this is a easy and low cost alternative.
It's a simple product to allow those of us who don't want to run wires to rear speakers to enjoy 5.1 sound. The installation and setup were trivially easy. The system works just as it's supposed to with no weird hiccups, sound artifacts, buzzing, noise, etc.
This unit seems to technically operate fine right out of the box, and though it only has wire terminals, you can hack your own RCA plugs if necessary. But there are two major downsides:1) It adds a noticeable fuzz (like white noise) for high frequency sounds, meaning attached speakers must have their treble turned up individually from the full system, then the output volume turned down on the Rocketfish. This offset disrupts the overall audio balance in a way that's difficult to fine-tune.2) In addition, the unit adds a perceptible audio delay of 15-20ms, meaning with a gain-balanced setup there's a fair amount of echo introduced.
Answer: That's what I did. I use one for two rear speakers, the other is for the other two rear speakers. No wire pulling under the floor over the floor! It works like a champ. Only negative is when I have a power flick, I have to turn the two remote boxes back on individually. I assume your sound system already has 7.1 capability, you just were using 5 speakers.