Taken from : http://www.macnn.com/reviews/iskin-cerulean-tx+rx.html
iSkin CERULEAN TX+RX
September 27th, 2007Wireless solution for your iPod and speakers or headset.
The iSkin Cerulean RX+TX is an interesting offering from the Toronto -based company that drifts a little from their mainstream products, which are mostly iPod silicone cases.
Bluetooth transmitter and receiver
The product comes packaged as a Bluetooth transmitter and receiver.
The TX unit is the transmitter with a rechargeable battery inside. It can be charged via USB or an optional AC adapter. The RX unit has no such battery and must be powered off USB, AC, or use the power of a dock connector speaker accessory that is capable of charging an iPod.
The RX unit receives transmissions from the TX unit and then plays those transmissions either out of its dock connector or out the lineout port on its side. It has a USB port on the side of the unit for powering the unit when it is not used with speakers equipped with the dock connector.
The TX unit can transmit sound from USB, where it shows up in the Audio System Preferences, or from an iPod. The RX can play audio output through a 1/8" mini plug, or through the dock connector. The result is that you can use the iPod video as if it were a remote control with screen, playing wirelessly through a dock-connector or mini jack enabled stereo.
I like to test audio products from 20Hz to 20kHz to see what frequencies reproduce without distortion at a consistent volume level when the source is a consistent dB level. This lets me know how accurate the sound reproduction is.
20Hz is lowest at which the Cerulean RX+TX work. 13000Hz is about the highest at consistent volume and 19080Hz at best with reduced volume.
I then tested the same set of speakers in a wired setting, and found that wired mode is consistent. From this, I can believe that any limitations I heard were from the speaker set I was using. Bluetooth often gets a really bad rap for audio, but my experience is that the Cerulean RX+TX had no problem with frequency range.
When the TX is connected to an iPod I noticed that it uses the headphone out, not the line out, so the volume control works. Whether or not the volume from the RX is loud or soft depends upon the efficiency of the amp or speakers on which it is docked.
By pausing and playing the iPod repeatedly, I was able to hear what sounds like the drive spinning up and down coming through the output of the RX. This sound is a quick high-pitched whisper-quiet whine that quickly glissandos to a slightly lower pitch. I was able to repeat this, but don't consider it to be an outstanding flaw. It does not seem to be present or noticeable in regular use.
Anytime that I change source on the TX, I have to unpower and repower the RX in order to reliably get it to receive again. It does not appear to always be the case that this is needed. In a few instances, I was able to simply change TX sources and it re-paired without further interaction. Bluetooth devices require pairing, but because this is Bluetooth audio, that repairing is what is taking place on re-applying power.
A Note on pairing: I found that using the "passkey options" button in Mac OS X's Bluetooth device setup and specifying an empty passkey helped it to pair with the computer when I wanted to use the computer audio directly over Bluetooth to the RX.
Price Per Foot
I'm compelled to mention cost. The question you have to ask yourself is this: Is it worth $149 to turn your iPod into a remote that works for up to about 30 feet away from the stereo? If that feels reasonable, then this product might be for you.
Overall, the RX+TX is a welcome product, particularly if you have speakers with a dock connector. Using the iPod or using the USB connector is easy, and once you get it paired, it works great. Of course, it will only sound as good as the speakers to which you connect it, but don't let that stop you - when used with the iPod or iPhone, it gives you all the flexibility of your iPod, as a remote control.
Edited by Ilene Hoffman, Reviews Editor
Good frequency range. Easy to use. Cons
Pairing is annoying when you have to re-apply power to the devices in the right order. Cost. Drains iPod battery more quickly.