The Marsh. I have owned both the Marsh A400 and the Bryston 4bst. Marsh A-400 is more neutral and lively sounding than the Bryston, and has superior bass definition (not quantity). It does not need much warm up time to sound good and would be a good match for the Vandersteens which can sound a little too rich.
Bryston 4BST, sounds veiled, less transparent and less neutral when compared to the Marsh, however, you may still want to consider it for other reasons such as warranty and reputed reliability.
Bryston 4BST, sounds veiled, less transparent and less neutral when compared to the Marsh, however, you may still want to consider it for other reasons such as warranty and reputed reliability.