The Infinity BassLink SM is an under-seat powered car subwoofer with a 125-watt rated amplifier and an 8-inch woofer. While it doesn't have the size or even the pristine performance of the 12-inch subwoofers I tested, it was the best performing under-seat subwoofer. And since it's so close to you, it doesn't need to be as powerful. You feel the bass just as much.
The Infinity BassLink SM and the JBL BassPro SL are identical in every way, save for the brand name and some minor aesthetic aspects, such as color. Both are manufactured by Harman, an explanation of why they are practically identical. However, the Infinity BassLink SM has a market price of about $170 while the JBL's market price is around $255.
The downside to the Infinity is the silver casing. Even if you manage to tuck it almost completely under a seat, the silver casing is very visible, making it an attractive theft item. As someone who has had his subwoofer stolen before, I know just how deflating it feels to have the heart of your sound system ripped from your car. If this is a concern, as it is with me, the $80 difference in price might be worth it for the black casing of the JBL BassPro SL. The black blends into the shadows much better and doesn't attract attention from the wrong people.
To grade the subwoofers, I evaluated the performance of the bass with high-end car speakers to gauge the balance within the mix. I also disconnected the speakers and evaluated the isolated bass performance, listening for distortions, clipping and the other nuances.
The BassLink SM earned an A- grade for the overall performance. This was the best performing under-seat subwoofer. The performance got a little rough near its maximum levels, but this is expected with most subwoofers and was minor compared to most under-seat subs. Overall, the performance was mostly comparable to the Pioneer TS-WX1210A. It was tight and accurate, though not nearly as big.
The size of the bass doesn't compare to the 12-inch powered subwoofers simply because the 8-inch woofer can't move as much air. In addition, the woofer is nearly flat, unlike the deep scooping woofers of the larger 12-inch subs. That said, it still received a B+ grade for size – the best grade for an under-seat subwoofer. As I tested it, the bass was big enough to move this 10 pound device across the floor. And since you literally put this subwoofer under your body, you feel it just as much, if not more, than the bigger subwoofers designed for trunks.
Power & Control
The built-in amp is rated for 125-watts of continuous power. While this certainly isn't the most powerful car subwoofer, it's good enough for an under-seat sub. You don't need as much power with the bass so close to your body. As such, the relatively weak amplifier is not a major concern.
The controls of the BassLink SM are excellent, receiving an A for ease of use. With six controls, you can really dial the subwoofer into your car's acoustics and your personal preferences. The only downside is the lack of a remote. It has a port for a remote, allowing the driver to control the volume without reaching under the seat, but the remote doesn't come with the subwoofer. You have to purchase it separately.
As an under-seat subwoofer, the size is very good. Only the Kenwood KSC-SW11 is smaller. With a height of about 2.75 inches, it should fit under most driver's or passenger's seats without much trouble. You can also put it under the bench seats or even in the trunk. However, the further you put it from the driver's seat, the less impact the smaller bass has and the lack of size in comparison to the larger subs becomes more obvious.
The Infinity BassLink SM earned my pick for the best under-seat subwoofer because of its tight performance and the big bass for such a small 8-inch subwoofer. It certainly doesn't feature the power or size of the 12-inch powered subwoofers, but this doesn't mean you won't feel it all the same. The control setup is very easy to use and provides exceptional tuning abilities. If you don't want to sacrifice trunk space, the Infinity BassLink SM is the best under-seat subwoofer, despite the eye-catching silver enclosure.