Nobody will ever confuse an Infinity Primus 150 bookshelf speaker ($99) with a satellite from a home theater in a box. The 150 is too big and too well finished to be mistaken for a lesser competitor, and its metal woofers and tweeters just don't exist in all-in-one systems.
Measuring 12.75 inches high, 7.5 inches wide, and 10.5 inches deep, the 150 is medium-size. The very solidly constructed design weighs an unexpectedly heavy 13.5 pounds. Black "wood grain" vinyl is the one available finish, and the removable grille cloth comes in black only. Infinity offers two other bookshelf models: the smaller Primus 140 ($89) and the bigger Primus 160 ($129).
The 150's magnetically shielded 5.25-inch woofer and 0.75-inch tweeter use Infinity's proprietary Metal Matrix Diaphragm technology. These anodized-aluminum drivers supposedly generate lower distortion than their more common plastic and metal counterparts. The keyhole slots on the rear panel and the rubber bumpers ensure easy wall-mounting. And thanks to the front-facing port, being up against a wall won't adversely affect the 150's sound.
We used a pair of 150s with two of their Infinity siblings: a Primus C25 center speaker and a subwoofer. The 150s' laid-back treble may lack the detail of, say, PSB Alpha Bs, but the Primus models are commendably easy on the ears. Even at the end of long listening sessions, they sounded great.