The 60 pound weight of each A-21 has been a bit of concern for me , Parasound assured me that there was no need to add rear rack supports for the amps, the supplied front mont brackets would be work well. This evening I decdied to try one of the amps in the racks, there are 3 screws on each side of the chasis that secure the bracket to the amp. The 4 screws then secore it to therack, once it was in place the amp hangs very securely, with no up or down movement when applying some pressure on the rear of the amps.
So it seems that MD and Parsaound know more than I, as I had doubts about ony a few small screws fully supporting the weight of the amp.
