We sell both and BOTH are outstanding amplifiers! The A21 will actually outperform the Bryston on speakers that are very hard to drive. If you want high current, then go with the A21.
You mentioned the "4-Bst", go with the newest version the SST. In comparison between the A21 and 4B-SST, the Bryston is the better sounding amplifier for music based critical listening. In addition, the Bryston warranty is second to none in the industry.....But, it no longer transfers to a second owner without receipt and registration. And, they strictly enforce the rule!!!
You mentioned the "4-Bst", go with the newest version the SST. In comparison between the A21 and 4B-SST, the Bryston is the better sounding amplifier for music based critical listening. In addition, the Bryston warranty is second to none in the industry.....But, it no longer transfers to a second owner without receipt and registration. And, they strictly enforce the rule!!!