Hi,
I own the Xtrememac Airplay 2 transmitter
http://www.amazon.co.uk/Xtrememac-Airplay2-FM-Transmitter-White/dp/B000CS64AA
and I'm reasonably happy with it. Obviously, only use this if there is no option of directly connecting the Ipod into your car stereo as the quality is OK at best. I bought mine as I travel in lots of different cars and most do not have any 3.5mm inputs. I chose this one as it met my particular needs well (your needs may be slightly different). The pros and cons of this particular models are:
PROS:
- strong signal so works in every car I've tried it in. Some cars (e.g. Jaguar X-type) have the radio antenna hidden in the rear bumper and so most FM transmitters are not strong enough for the car stereo to pick it up well.
- can "boost" the signal by attaching the standard Apple USB docking cable to the bottom of it and so forming an extra boost to the internal aerial.
- Can store 3 independant frequencies so you can easily switch between them when travelling around.
- Fully tunable frequencies from 88.1 to 107.9 in 0.2Mhz steps. Therefore in areas with lots of stations you can usually find a "quiet" frequency to broadcast on.
- Can be switched to "mono" mode to increase the signal strength further if really struggling. The only place I've needed this so far is in areas of Italy and LA where every frequency has had some kind of station broadcasting on it.
CONS:
- Does not "lock" onto the bottom of the Ipod so can easily fall out. (I've made a little box / cradle that not only protects the IPOD but also holds the transmitter in place).
- Sometimes freezes so have to unplug it and plug it back in again to "re-boot" it.
Overall not a bad transmitter. Sounds quality is generally a bit flat and lifeless but in most cars with the background road and wind noise it's OK. I've heard quite a few of the other FM transmitters on the market and the sound quality is as good as anything else out there.
Hope this helps,
Sam
http://www.amazon.co.uk/Xtrememac-Airplay2-FM-Transmitter-White/dp/B000CS64AA