A few months back I bought two Speakercraft BB-2125 commercial amps, same target market.
Here's a snap shot of the inside I found on google.
I had considered it was possible Speakercraft, Sonance and Niles shared the same OEM, but if they do the quality may vary greatly. One of the amplifiers was DOA and the other made a lot of noise, both the amp itself as well as line noise at the speakers. Generally unacceptable performance for any level of HiFi. I've not tried a Sonance yet, but the exterior quality on units I've seen seems in between that of the Niles and Speakercraft with Niles being superior to both in fit and finish. The Speakercraft quality was alarmingly poor. The front panel flexed from the top of the chassis on both units. I could have easily stashed my junk mail in through the gap of the front panel and the chassis while I was prying.