I'll just use hybrid bridge per channel.
Why spend more than is technically necessary. A single pair of Schottky diodes will be more than sufficient to provide the connections to ground for both channels. Separate 6CA4s (1/ channel) very effectively isolate the 2 amp sections from each other. Each channel will have 150 mA. of DC available to it. That's plenty for PP AB1 EL84 "finals".