@ihcho I had to deal with a similar issue though my amp did come with a very good stock 20A cord.
However, the stock power cable (which I reiterate was quite good and capable) was surpassed by my aftermarket power cord, a 15A standard cable, with a 20A > 15A IEC adaptor.
I purchased another one of my aftermarket power cables with a 20A IEC termination and a 15A male three prong end. This surpassed the adaptor (same power cable, but new). [Emphasis - new without adaptor beat fully broken in with adaptor].
I encourage you to try both approaches, but I believe re-terminating will offer superior results.
All the best.
However, the stock power cable (which I reiterate was quite good and capable) was surpassed by my aftermarket power cord, a 15A standard cable, with a 20A > 15A IEC adaptor.
I purchased another one of my aftermarket power cables with a 20A IEC termination and a 15A male three prong end. This surpassed the adaptor (same power cable, but new). [Emphasis - new without adaptor beat fully broken in with adaptor].
I encourage you to try both approaches, but I believe re-terminating will offer superior results.
All the best.