Is there a more powerful version of amitriptyline for curing chronic pain?

No. Amitriptyline is a tricyclic antidepressant, similar to drugs such as Cymbalta (duloxetine) and savella (milnacipran) which are known as snris (serotonin/norepinephrine reuptake inhibitors). None cure pain; they increase nerve chemicals that decrease pain. You may respond better to one vs. Another but none are "more powerful" than any other. The snris are touted to have less side effects.
In a way. Amitriptylene is a first gen tca, tricyclic antidepressant. As mentioned these medications increase serotonin and norepinephrine to help the brain decrease pain input. However it has a lot of side effects with one of the worst being sedation. Desipramine is a newer tca that is equally good for pain but with less side effects. This allows your doctor to titrate to a higher, more effective dose.