Power cord length and monoblocks

Do power cords feeding monoblock amplifiers in a 2-channel system have to be the same length as speaker cables need to be?
...only approximately... as long as difference in lengths less than 20m...
It's unlikely that the wires behind the wall are of equal length either, so I wouldn't consider a few feet pc cord length difference critical.

Power-wise, it' not a concern. A 10 ga wire will lose half a volt for every 10 feet at 20 amps, and since (good) power supplies can regulate within power delivery tolerances (114 to 126 volts), you will need a difference of about 150 feet to make an effect in this example.

Sonically, who knows. I'm sure some will say they have experienced or perceived a difference. And some will say they have not.
Even with a cord that uses specific geometry and tuning, i would not consider this critical. What i would consider critical is the difference in ground potential when tying into two or more different circuits / outlets. Many people have all of their line level gear on one outlet and each monoblock on their own outlets. The potential for a ground loop increases with each additional circuit / outlet that is added to the system. Sean

Sean, I believe I've read that the ground loop potential can increase when using different power cord lengths, which I guess would imply that the greater the difference, the greater the potential for an audible problem. Do you agree with this position? I'm further guessing that Aponter4 wouldn't be asking this question if he wasn't plugging both monoblocks into a single outlet that was significantly closer to one amp than to the other, meaning that the cord differential might be on the order of 2-3 lengths...
Zaikesman, the distance difference from the outlets for the amps would be ~6 ft.; one amp is 4 ft from the outlet and the second one 10 ft. away. That's 2.5 lengths.
They don't call me Carnac The Magnificent for nothing... ;-)