Can a power surge cause amp to clip?

A power surge can potentially damage an amplifier. The first thing you want to do is check the fuse(s)  inside. Technically, fuses in audio gear (specifically) can last forever, but when accepting any kind of interference, they may take the "hit" to protect other internal components.

Also take a look at the capacitors and the ends of soldering joints from cables inside the amp. If you see any red (mercury) or corrosion (brown) that is a bad sign.

If the problem persists, fixing it would involve what I explained above. Advanced stages of failure could include the amp shutting off by itself or making sounds while powering up. 

OP,

I believe the next step would be to email a repair specialist in your area. Calling them first and explaining the problem will get them interested in working for your benefit.

In the follow up email, include a high resolution picture of the internals. This way, they are able to zoom-in and take note of anything that appears to be unusual.

In rare cases, bad capacitors do not show any signs of damage (same with fuses). The static crackling sound is usually a sign of this or a power transformer that is failing. If not that, the mainboard or part of the motherboard responsible for input/output switching may require some looking in to.

In order to correctly determine the cause/solution, a repair person would need to test your amp with various tools - including a multimeter. Along with this, a schematic would enable them to fully repair the unit if it requires servicing.