Fellow gear reviewer Eric Tischler sent me this helpful tool. It's a key fob with a 1/4'' plug and four LED's, one for power and three for -32, -22, and -16 dBu signal level. You plug it into a jack, squeeze the body, and read signal level. Great for finding a break in a signal chain. In the ideal world, you'd be able to see with your eyes whether a cable was passing signal between devices. This is the next best thing. Although it comes optimized for reading instrument level signals, the included manual describes how to pop open the device and mod it to read levels more appropriate for +4 dBu operation; too bad there isn't an external switch. A true audio geek would carry this along with XLR and RCA adapters on the same keychain. Pretty much the only thing that'd make it cooler is if it had a built-in LED flashlight to help you see into the back of racks. ($24.28 direct; www.fongelectronic.com)