What goes surround: Death and taxes aren't the only things in life worthy of the tag "certain." Equally unavoidable is the obsolescence of technology standards: What was cutting-edge yesterday will be so last week by tomorrow.

In the realm of portable sound, stereo is no longer the best. If you really want to hit the right note, you need 5.1-channel surround sound. Originally designed for a theater setting, a 5.1 system has three speakers in front of the listener and two behind, plus a subwoofer. Making such a sound cocoon portable is technically feasible, but few of today's plethora of portable music players deliver more than basic stereo reproduction.

Electronics maker Sizen Corp. is offering something of a solution with its iM10 sound adapter. A tad larger than a matchbox, the iM10 is a square gadget that you connect in between your portable device and your headphones.