The Bryston 4B SST Pro is a stereo power amplifier, and at that is one of the best of it's kind. I've used this power amp with a pair of passive ProAc Studio 100's at the studio where I work. These aren't our main monitors, rather we set them up occasionally as an extra choice for engineers, and the power amplifier that we always used in the Bryston 4B SST Pro. I don't know a whole lot about the background of this power amplifier, but everyone at the studio agrees that it's one of the best they've used before. Sometimes we'll also use these with our Yamaha NS-10m's, but for the most part they are used with the ProAcs. This is a pretty heavy piece of equipment, so we tend to keep it and one spot, as it does take up about three to four rack spaces if you wanted to keep it in a traditional rack casing. The 4B SST Pro has an array of different connections for you to choose from, starting with dual XLR-1/4" jacks, and followed up with RCA and traditional speaker cable jacks for hooking up your monitors. I'm not sure exactly how much power these deliver, but it should absolutely be enough (maybe even too much) for your passive monitors. These days most monitors out there won't require an external power amplifier since most of them have one built in, but there are still plenty of monitors out there that will require a power amp. Especially in a professional studio environment, it's extremely important to have a good amp to go with your passive monitors. With the Bryston 4B SST Pro, you're getting one of the best power amps available. The only downfall is the price, but as always you get what you pay for, and what you get here definitely lives up to the price if you can afford it!
We bought this amp for mastering, on IB2S PMC. We are extremely pleased with the sound reproduction. I had the curiosity to use the amp on other monitors, Quested VH3208 I was moderately satisfied with the old amp (reputedly excellent).
With the Bryston, these speakers will reveal fabulous, suddenly we bought a second 4BSST Pro.
Connected to any speakers, it transfigures, everything is detailed, excavated in the extreme. This saves a significant time in mixing. This is the price (very high) makes sense. For an amateur, half a day more or less of a mix makes no difference. Professional structure, on the other hand, it is worth its weight in silver. So yes, Bryston is expensive, but completely justified. To know that this model is built like a tank (equivalent to building two separate amps, with a power supply for each channel), and guaranteed 20 years. That happiness.