Although Digi will not be "officially supporting via our compatibility documents" the older Magma 6 and 7-slot chassis with PT 5.1 it is not due to any functional problem with these chassis. The reason for the change is that there are new MAGMA 7-slot rack-mount expansion chassis, models P7R-D1 and P7RQ-D1 coming to market that have replaced the older chassis in our compatibility testing grid. These new chassis are very similar to the older chassis, only incorporating some power supply advancements. This announcement in no way implies that the older models will not work with PT 5.1. It means that due to the scope of testing required and the similarities to the new Magma chassis, these chassis were not put through the stringent testing that Digi requires for listing on the compato list for 5.1. These chassis did in fact go through basic testing, and no problems were found. As you will notice in the last sentence of the announcement, Tech Support is still going to support PT 5.1 customers with these older chassis assuming that the problem is not related to a damaged or malfunctioning chassis. Rest assured that we will honor that commitment.Bob LanglieDirector of Customer ServiceDigidesign Here's the full announcement:Digidesign announces support for the new MAGMA 7-slot rack-mount expansionchassis, models P7R-D1 and P7RQ-D1.The new MAGMA 7-slot rack-mount expansion chassis, models P7R-D1 and P7RQ-D1, are now officially supported with Pro Tools Mix and Mix Plus systems! Additional requirements are Pro Tools software version 5.1, Mac OS 9.x, and MAC B & W G3 or newer CPU. Both of these models include a standard 1.0 meter expansion cable; optional configurations are available with 1.5 meter cables. The P7RQ-D1 units provide for "quiet" operation using "Silencer" power supplies. Digidesign will include these new models in testing of future software releases.At the same time, Digidesign will no longer be including the MAGMA 6-slot chassis (#PCI6DR ), and the older MAGMA 7-slot chassis (#PCI7RX300V), in the test cycle for future Digidesign software releases, and therefore will not be able to officially support these chassis with Pro Tools software versions 5.1 and beyond. However, the Digidesign support department will continue to provide Technical Support to Pro Tools 5.1 customers who are using either of these chassis while the problem is not related to a malfunctioning chassis.