The Trendnet TPL-420E2K delivered TCP throughput of 94 Mbps, which is somewhat slower than the 115 Mbps average of the Zyxel, but still faster than the products without the optional enhancements. Either product is worth considering for back-up devices or entertainment centers that need high-bandwidth for streaming media, something Wi-Fi can't always provide.
Like other HomePlug AV2 kits, the Trendnet TPL-420E2K ships with two small boxy adapters that plug directly into wall outlets. Each adapter has a gigabit ethernet port, and the kit includes two five-foot ethernet cables as well. The size of the adapters might block the second outlet (especially if you need to plug in another wall wart).
To create the power-line network using an existing Wi-Fi router (the most likely scenario for most people), you plug one of the adapters into a free wall outlet and run a cable from its ethernet port to a free LAN port on the router. Now you can plug in the second adapter to a free outlet near a device you wish to add to your network and run the second cable from the adapter to the device's ethernet port.
Use a wall outlet rather than, say, a power strip, which likely has surge-suppression technology that can degrade the ethernet signal.
The technology is plug-and-play, meaning it requires no additional setup to work. Should you wish to add another HomePlug device, however, you'll need to sync it to the network, typically by pressing buttons on both the new and one of the existing adapters (or by typing the adapter's unique identifier into a software utility that most vendors provide). Data is encrypted using 128-bit AES.
A HomePlug AV primer
For those who don't follow the minutiae of HomePlug AV standards for networks that use existing electrical wiring, HomePlug AV2 (the third-generation HomePlug spec) includes both mandatory and optional components. The first wave of HomePlug AV2 products were based on the mandatory components only, which promised nominal network speeds of up to 600 megabits per second and delivered 60 to 70 Mbps in our real-world tests.
The second wave of HomePlug AV2 products utilize the MIMO (multiple input, multiple output) concept first introduced with high-speed Wi-Fi routers. But this requires using all three wires in your home's walls: line, neutral, and ground. If you live in an older home that doesn't have grounded wiring (and three-prong outlets), you won't be able to use this type of power-line adapter.
Even if your home has grounded wiring, you should be aware that the quality of your electrical circuitry can significantly impact the performance of power-line networking devices. In addition to running tests in the same location (my home) that I used for the last group of product tests, I tried out the Trendnet TPL-420E2K in a different home and was unpleasantly surprised to see that speeds in one room were dismal 20-25 Mbps, or even slower than the slowest AV 600 products. Yet in other rooms the speeds equaled those recorded in my own home. A Trendnet spokesperson attributed the poor performance in the one room to incorrect (or possibly crossed) wiring. Sadly, there's no obvious way to determine beforehand whether your network environment suffers from such flaws.
Prices for power-line adapters have dropped significantly since our last roundup, with the street price of ZyXel's PLA5405KIT dropping the most: From $140 in January to $93 today. Trendnet's TPL-420E2K carries a list price of $130; we found it selling online for $110. It pays to shop around, though. Amazon has great prices on some power-line adapter models, but the Trendnet TPL-420E2K was available there only through one of its third-party merchants--Interlinkseller--which had it listed for sale at $162, $32 higher than Trendnet's suggested retail price.
Given that ZyXel's adapter is both faster and less expensive than Trendnet's, the ZyXel PLA5405KIT remains our top choice in high-speed power-line adapters.