The digiZoid Z02 Personal Subwoofer is not a subwoofer at all. Instead it is an "analog sound enhancement device" which will boost the volume of your 3.5mm source and provides bass boost. The amplification means that your source (usually a portable player or phone) will save battery and the bass boost can correct the typical failing of most headphones. At $120, the digiZoid ZO2 isn't cheap, and it isn't without its flaws, but we're betting most audioholics wouldn't mind getting one for Christmas. Discuss "digiZoid ZO2 Personal (not a) Subwoofer Review" here. Read the article.