Gathering "stuff" to upgrade audio, already have a Kenwood DNX9900HD HU to go in, installing Focal P165v30's for the front and yes doing rear fill with a set of Focal's 3 W2 Be midrange speakers to be powered by the HU. Not putting in a sub, so that is not part of the equation.
Came across this yesterday at a local shop, they had quite the selection but salesman was pushing this with my setup. Seems to getting some good reviews - Pioneer PRS-D800 Compact in size, easily can fit under the seat, pure power with no internal crossover (that's how I am understanding it at least)
Specifications
Number of Channels: 2/1
Maximum Power Output: 600W
Continuous Power Output (2 Ω, ≤ 1% THD+N): 150W x 2
Continuous Power Output (4 Ω, ≤ 1% THD+N): 125W x 2
Continuous Power Output Bridged (4 Ω): 300W x 1
Frequency Response: 10Hz to 80kHz
Total Harmonic Distortion (4 Ω): < 0.004% (1kHz)
Signal-to-Noise Ratio (IHF-A Weighted, at 1 kHz): >105db
Dimensions (WxHxD): 10" x 2" x 4-1/8"