PAC Ground-loop isolator

Basic Info
Product name: PAC Ground-loop isolator
Model/Part #: PAC SNI-1/3.5
Website: http://www.pac-audio.com/productDetails.aspx?ProductId=193&CategoryID=31

Size: Wire approx 3-4 feet (.91m - 1.22m), box is roughly 2"x2"x1" (5.08cm x 5.08cm x 2.54cm)
Weight (from UPS): 0.185 lbs [83.9 g]
Retail Price (MSRP): $16.95 USD

Purchased From: Sonic Electronix
Cost: $13.56 base + $4.95 shipping = $18.51 total

Description
One of my favorite features of my car is the ability to listen to my audio player by means of the headphone jack in the center console. I've long since given up on trying to deal with the constantly shifting radio frequencies and interference and the frankly awful performance of those self-broadcasting iPod and GPS solutions. Even when you have a good signal it's awful.

So, when I got my car one requirement I had was an audio-in jack so I can listen to Radiolab and This American Life with some respectful fidelity.

What's that whine?
This works like a charm - until the fateful day that you happen to try to both the music player to the car for audio-in and to the cigarette lighter for power at the same time.

What you get - in this scenario - is what I would originally refer to as 'Engine Whine', and later found out is the effect caused by a ground loop. In this scenario, I would get a constant, high-pitched whine that would go over my speakers whenever I plugged in, regardless of whether the device is on or playing. This whine would also vary pitch in response to the amount of RPMs that the engine is producing; it would get higher whenever I stepped on the gas and lower whenever I would stop accelerating.

The sound, the effect caused by a ground loop, is (apparently) caused by having devices which are "competing " for ground, which I've read is caused by different potentials between the devices. I'm not versed in the Electrical nuances of an automobile, so I'm not sure how much the above applies, though.

Anyway, after googling around a bit, I was reasonably sure that the device that I needed was called a 'Ground Loop Isolator', which is supposed to filter out the condition that causes ground loops. Unfortunately, most of the devices appeared to be something that is added into the audio system itself, rather than an easy plug-in device, and most seemed to connect through RCA connections. None of this really helped.

A Potential Fix
Fortunately, I was eventually able to find a ground-loop isolator that had headphone-jacks at an online store called "SonicElectronix". Since the price was reasonably low (~$20 shipped), I elected to gamble on the effectiveness of the device and on this retailer. I made an order for the device. .

Thoughts - Retailer
Since this is a review on the device, I'll keep this to a short note to say that my experience with SonicElectronix was very positive. The device shipped to me fairly quickly and with minimal packaging waste. There were no issues whatsoever with the transaction.

Thoughts - Device
As soon as I got the package, I eagerly grabbed my keys and my iPod. I plugged it all in, started my car, turned the radio on, and pushed play on my device. What I got was the crisp, clear sounds of my Radiolab podcast, and not a hint of noise. Brilliant!

Overall, this device works wonders. It's worth every penny that I spent on it. I've since tried it on my laptop, which makes all manners of noise when plugged into the wall and into my receiver at the same time. Same thing. No ground loop noise, just the sweet sounds I was expecting. Suddenly the biggest problem with the isolator is where to keep it while the other one ships - in the car or in my living room.

The only negative item that I feel is worth mentioning is the fact that this is a very plain-looking device. As someone who fancies a Radio Shack or American Science and Surplus from time to time, this was of no great import - I've long since realized that most of the greatest electrical wonders come looking fairly boring. But if you're looking for items that looks slick and Monster Cable-ish or iPody, this device may not sit well.

Summary
Overall, I would highly recommend the device if you get noise in your car or home audio system, especially if it's noise that is correlated to some sort of work (computer operation or engine load), and one that goes away when you remove a power source and work off of battery. A ground-loop isolator is a very cheap and effective way to remove all that annoying noise.