If I remember the a500 DMA channels correctly some are from gary, some from denise and the remainder from Agnus. Depends which DMA channels are used by the a590 to bring data from the drive into the motherboard then ram via the 86pin side expansion bus.
The chipset DMA channels are controlled by agnus, denise & paula just gets/supplies the data. These can only access chip ram.
DMA using the expansion slot are different. They are like Zorro bus masters, they control their own DMA channels and just drive the bus using an arbitration scheme.
