Both Polk Audio and JBL are great brands with reputations for quality products. Polk Audio tends to lean more toward home and professional studio with their product lines, while JBL manufactures home, professional studio and concert gear. These in-wall speakers are nearly identical with only a few subtle differences. The Polk Audio uses a mineral filled polymer-composite cone, which will result in a crisp but slightly bright sound, and the JBL uses an aluminum cone that is polymer coated, resulting in a more consistent speaker motion that is somewhat flat. JBL compensates with design, which is JBL's strong point, and a larger tweeter.

Polk Audio's in-wall is designed for use in environments that are prone to moisture, such as bathrooms and saunas. The rubberized woofer and titanium tweeter in the JBL will also withstand moisture but for long term exposure to that type of environment the PolK Audio speaker would be more suitable. (Marine/Boat speakers would also work well) The primary use of these speakers is to support a Home Theatre, and in that respect the JBL posts slightly better performance numbers, mostly due to the crossover frequency. Neither of these units are shielded magnetically and so should not be used in close proximity to a CRT or certain other types of displays. One small detail might shift this comparison between Polk Audio and JBL, and that is JBL swivel moounts for the tweeters. This means that if you need to rearrage the seating area you don't need to physically relocate the entire speaker, simply reposition the tweeters.

The basic considerations here are a bit of brand loyalty and available cashflow. If you plan on using these speakers to supplement sound in an area with moisture then Polk Audio should be an easier pick, however the JBL speakers are significantly less expensive.