Performance
The PA-X2150 performed quite well during our test session. The amp falls a bit short of its power ratings, but not by enough to really matter. The 2150 produced 129Wx2 into 4 ohms, 163Wx2 into 2 ohms, and 404W bridged into our 4-ohm reactive load. I’ve always been sort of a stickler for power ratings, mainly because there’s not much of an excuse for them not being accurate. Both Ohms Law and amplifiers have been around for a long, long time. On the other hand, I’m pragmatic enough to let a difference of 15 or 20 percent slide because it’s only a dB or so and most people couldn’t really tell the difference.

Noise measurements show the PA-X2150’s A-weighted noise floor to be a respectable 103 dB below the amps full output. Turn on/off noises measured about 45 dB and 35 dB SPL, respectively, which is a little high by competition standards. However, if you don’t compete, it’s hardly going to be a problem. Crosstalk measured a rather high –28.7 dB, although to be fair I should point out that this figure occurs at 20 kHz and represents the worst case across the full audio bandwidth. You need about 30 dB of channel separation to properly reproduce stereo program material. In the more critical midrange frequencies, the 2150’s crosstalk measures about –50 dB.

Beyond the numbers, the most impressive thing about the 2150 is the fact that the amp runs incredibly well. This is a very stable and well-behaved amplifier; it completely aced all of our automated measurements, requiring no manipulation of the test setups, no funky grounding tricks, and no doing measurements the hard way (manually). The vast majority of the amps that we test will eventually exhibit some small idiosyncrasy during a test session. Most of these aggravations are pure lab-tech geekery and have little or no bearing on real-world performance, so they often go without mention. However, when any amp goes through an entire session without making me curse under my breath at least once, I have to give props.

Connections & Adjustments
Connections to the PA-X2150 include line level RCA inputs and outputs, high-level input (with supplied connector), telephone-style remote receptacle, 7/16-inch spade receptacles for power and ground, and 3/8-inch receptacles for speaker and remote turn-on connections. Adjustments include input sensitivity, remote bass boost (variable from 0 to +14 dB at 42 Hz), crossover mode selection switch, high-pass cutoff frequency (variable from 68 Hz to 730 Hz with 12 dB per octave roll off), and low-pass cutoff frequency (variable from 53Hz to 110Hz with 18dB per octave roll off).

Installation
The PA-X2150 measures 10” x 2.5” x 16” and may be capable of passenger compartment mounting in larger cars. The amp does require a sizable amount of real estate for its output potential, but this is a 129Wx2 amp with an awful lot of heat sink. Another bonus on the installation side is the straightforward layout of the amp’s control panel. It offers controls for all of the standard amplifier bells and whistles but manages to do so with a lot less clutter and confusion. One thing that helps is the omission of a bass boost control on the amplifier chassis. If you have a remote, why bother to include a control on the amp? When you can reduce cost and complexity at the same time, it can’t be a bad idea.