The output section of this amp is a little unusual. Like I said, it looks like a stereo amplifier. The output section uses the middle half of the amplifier, and each side is a mirror image of the other. The usual secondary filtering caps and inductors are duplicated, as well as seven output MOSFETs down each side of the heatsink. That's a total of 14 output devices, each capable of handling more than 100 watts. The two sections appear to operate independently up to the point of a cross-wound toroid, after which the two outputs are tied together and travel through a relay and hash filter to a parallel set of speaker terminals.
Performance
On the bench, the VRA1000D held up pretty well. While the frequency response looks a bit truncated (217Hz on the top), keep in mind we reference our results at -1dB. The top end is dictated by the always-present (and adjustable) lowpass crossover, with a -3dB of 250Hz, exactly as advertised. Turning off the subsonic filter revealed a low-end of 15Hz, again at -1dB.
Unsurprisingly, the amp made more than its advertised power at each specified impedance load with the exception of a 1-ohm with 12.5 volts of input. The signal-to-noise ratio was at >95dB-lofty for Class D and, again, much higher than stated.
I turned my attention to the crossovers, which were a little sloppy, both in slope and -3dB points, though I admit that the digital processing we've seen in some amps recently has spoiled me. The 250Hz top end was dead-on as I mentioned before, but the slopes were somewhere between 12 and 18dB/octave. Their design indicates the intention of an 18dB/octave slope, as evidenced by the three-gang control pots, but there is so much filtering happening in such a narrow spectrum that the filters never really get away from each other and settle out. In reality, this isn't a huge deal and the crossovers worked well in the car. And, speaking of slopes, the subsonic filter can be a huge benefit when used with a ported sub enclosure.
The input level is a quite broad 130mV to 8.1 volts, thanks to a multiplier switch (selectable between x1 or x3) connected to the gain pot. This affords the VRA1000D the flexibility to accept signal from the 2-volt outputs of a typical head unit or the 8 volts of a signal processor.
The short circuit protection worked repeatedly, but the thermal protection was never triggered. I simply couldn't get the unit hot enough to shut it down. It felt hot to the touch around the power supply section, but flat heatsinks always feel warmer because they make more contact with your skin.
Manual
While we were informed that our test subject is indeed the real deal, we were also told that it was a pre-production sample, one of many the company shipped in from its overseas manufacturing plant for final analysis. Like other pre-production units, the VRA1000D design was finished before the manual, so we didn't get to sample the installation instructions.
Listening
I always find the listening portion of amplifier tests the most fun, though maybe a little stressful on my subwoofer. For this audition, I ran a dual 4-ohm (wired in parallel for a 2-ohm load) 12-inch sub in a sealed 1.5-cubic-foot enclosure in the trunk of my LSE. The sub is rated for 600 watts continuous, but it sounded as if the VRA1000D was putting a lot more to it. This meant I had to exercise some self-control, which is never fun.