My experience with a new set of speakers was similar. My VR4 Gen III's were unlistenable when first played. I followed the manufacturer's recommended break-in of 100 hours of LOUD music & now 5 months later they sound fantastic.
Interestingly during this break-in process my amp apparently had never been run very hard & it finished breaking in too. It is 7 years old & I've had it just shy of a year. How do I know the amp wasn't broken in? I could smell an electronic smell coming from it the first two times I ran the VR's hard. My dealer suggested it had been run long & hard enough to finally heat up everything to complete the process. The manufacturer corroborated this.
Interestingly during this break-in process my amp apparently had never been run very hard & it finished breaking in too. It is 7 years old & I've had it just shy of a year. How do I know the amp wasn't broken in? I could smell an electronic smell coming from it the first two times I ran the VR's hard. My dealer suggested it had been run long & hard enough to finally heat up everything to complete the process. The manufacturer corroborated this.