These are Proceed (Madrigal) pure discreet mono amps capable of delivering 250W in 8ohms - that's about all you need to know.
You can read the user manual here - http://www.proceedaudio.com/manuals/BPA.pdf
and a contemporary review - http://www.avrev.com/home-theater-power-amplifiers/mono-amplifiers/proceed-hpa2-and-hpa-3-dual-triple-monaural-power-amplifiers.html
We have a matching BPA2 dual mono amp listed here too
The unit is available to view in Mountain View from 11am-7pm, Monday-Saturday. Add 3% for PayPal. Please note that California residents will be have to pay sales tax.