Hi Jan,
Of course, such a current draw by a chip amp is impossible, as I suggested, as you would need massive and quite impractical heatsinking amongst other things, which is obviously not the case here with (any?) chip amps. We are probably dealing with a max. of 25% of this 8A capability in reality, which is why I don't forsee any real problems here, even with only one diode device being used.
The surge potential is not quite so clear cut, though, and this is why I continually suggested that caution should be adopted, at least initially. If the switch is flipped just when the mains is at a peak of the AC, and the smoothing caps are seen almost as a dead short, who knows precisely what this can do by way of instantaneous current draw?
I don't measure the characteristics of very many diodes as I haven't found it necessary for any matching purposes or whatever (unlike most other semi-conductors which I match as a matter of course), but recently for another purpose I did check a batch of fairly mundane diodes, and found that their forward voltage drops etc. were remarkably consistent.
It is academic now, but although I don't presently recall quite why Metaxas advocated this multi-parallel diode arrangement, my guess is that it was related to keeping the mains impedance as low as possible, as this does have a sonic effect with amps (like Class AB) which don't draw current consistently. For this same reason I would also avoid deliberately adding any resistance in this path, however low this might be, in order to 'equalise' parallel diodes. In my experience, it should not be needed, especially in this instance.
I have always been keen to encourage others to try things out for themselves, as I (and I suspect many others) have learned a great deal about these matters by so doing, and in my own case over a period of some 40 yrs. In this situation where the voltage is low, and with very little current draw to consider, I don't forsee any serious danger or disasters occurring, providing a little common-sense and care is taken by Daniel.
I hope that things go well for him, but I am sure the exercise will teach him something worthwhile, even if for some obscure reason it transpires that his chosen diodes are not quite up to the requirements of this job.
Regards,