I'm no expert on internals, but I'm pretty sure you could save at least 1/2 of your memory by changing @amp_a from being an array of anonymous arrays (which has an RV, an AV and 2 SV's per element) to a straight array of scalars (only one SV per element).

Then, instead of carrying around your cumbersome, unpacked data, you can just unpack in the sort: 

my @sortamp = sort{ unpack(..., substr(...$a)) <=> unpack(..., substr(
+...$b) } @$amp_a;

[download]

It might be slow, but (hopefully) you won't run out of memory.

You don't mention what platform you're running on, but if it's little-endian, this ought to work (because the sort key is an integer at the end of your data): 

my @sortamp = sort{ reverse($a) cmp reverse($b) } @$amp_a;

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(A straight string compare with the most significant bit in front.)

In reply to Re: Sorting data that don't fit in memory by eg
in thread Sorting data that don't fit in memory by jeroenes

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