Every now and then, you stumble upon a cool little device which makes you think: "Why didn't I think of that?" Then you take it home and rapidly discover that what you thought was a nifty-keen piece of hardware has limitations and restrictions that make it far less cool than you originally thought. The net result is another hardware item that sits on the shelf, unused.

I had that "Aha!" moment when I first saw an ad for the Harman/Kardon EZ Link. The EZ Link (aka the DAL-150) is a little gizmo with an 8051-compatible microprocessor and a little bit of cache. You connect one end of the EZ Link to your PC via a USB port, and connect the other end to your home audio receiver via an RCA-style, coax digital audio connection. That allows you to play the MP3 collection residing on your PC through your home audio system. Sure, there are digital audio receivers that can do that, but they cost $300 or more, and the DAL-150 is a mere $150.

The review unit arrived in a small box. The EZ Link unit itself is quite small, and the size of the box was mainly to accommodate the installation CD.

Harman/Kardon EZ Link USB Connector

Harman/Kardon EZ Link RCA Jack

There are no indicator lights, no controls, just the RCA jack on one side and the USB connector on the opposite one.

I plugged the EZ Link into a system using an Intel D850MVSE motherboard. Windows XP detected the hardware, found the drivers in the CD drive, and installed them. One reboot later I had… nothing. The installation document shipped with the DAL is pretty brief, but also covered most of the bases. I was supposed to see a small "HK" icon in my system tray, like this:

It wasn't there, however. On top of that, the system became excruciatingly slow to boot -- and sometimes would hang on boot. Unplugging the EZ Link from the USB port would fix the problem. I then tried it on another Pentium 4 system, this time with an Intel 845 chipset. The same thing happened.

I wasn't quite ready to call tech support or throw in the towel. As I sat there, I realized that both systems I used for testing had USB 2.0 on the motherboard, in the form of the common NEC USB 2.0 chip. So I tried installing the DAL-150 on a system that only had USB 1.1.

Bingo.

Everything seemed to install just fine, and the HK icon now appeared in the tray area. So I shut down the system and installed a longer USB cable. I needed the longer cable so the DAL could reach the digital audio cable that was connected to my home theater receiver. I rebooted, and was presented with a continuous chorus of Windows "now we see the device … now the device is disconnected" chimes, repeated over and over again.

This forced me to replace my digital audio cable with a longer one, and use the original, 18" cable shipped with the EZ Link. Double-clicking on the HK icon in the tray yielded this screen:

At that point, things began working normally. When the EZ Link first fires up, the driver downloads a program to the 8051. Apparently, this process is extremely intolerant of timing differences or reflections on the USB bus. So USB 2.0 was out, as are long cables, at least until the software is updated. At least Harman/Kardon provides an update button on the minimalist software control panel for the DAL, but no new updates were available at the time of this review.

The DAL-150 either converts MP3 to a stereo PCM digital audio stream, or simply passes the MP3 stream through. It can handle MP3 files with resolutions up to 320kbps, which represents very good sound quality if you've used a good encoder. At that point, everything worked. Then one other limitation came into play: the EZ Link only works with Windows Media Player. Harman/Kardon even supplies a recent version of Media Player for users of Windows 98, Windows 2000 or WindowsMe systemes. If you use WinAmp, MusicMatch or any other MP3 player, you're out of luck with the way the DAL-150 works. Also, the unit doesn't have the bandwidth to handle playback of DVD movies, either, so you can't use it to pass Dolby Digital 5.1 digital streams.

When you use the EZ Link, it turns down the volume on the Windows mixer and shunts the output from Media Player, through the USB port and to the DAL-150. Playback on the home theater system sounded fine, with no added distortion apparent. So within the very narrow limitations of the product, it works.

However, I'm left scratching my head on this. The limitations are simply too great to be of much use. Sure, it's cheaper than a digital audio player, but at $150, it's not an impulse buy, either. It's small enough that notebook PC users could carry it around to play their music libraries on systems outside the home. But I could just as easily run a digital audio cable from my sound card to my receiver--and that's much cheaper than the EZ Link.

So here's another product that will sit on your shelf. It has potential, but requires a significant software update before that potential is realized. Until then, we can't recommend this for all but a very few users.

Harman / Kardon DAL-150 EZ Link Price: $150 MSRP www.harmankardon.com

Pros: Simple installation... Cons: ... if you don't have USB 2.0. Works only with Windows Media Player. Can't use long cables. Pricey for what you get. Rating: 5/10

Copyright © 2002 Ziff Davis Media Inc. All Rights Reserved. Originally appearing in ExtremeTech.