Sure! We can debug amp specific problems in the issue 9.
Thanks for the information!
It looks like this problem is not amp-specific, but might be caused by setting the default dtype to torch.float16.
E.g. this code should throw the same error:
torch.set_default_dtype(torch.float16)

device = 'cuda'
input = torch.randn(100, device=device)
n_fft = 100
hop_size = 10
win_size = 10

res = torch.stft(input,n_fft,hop_length=hop_size,win_length=win_size,window=torch.hann_window(win_size).to(device,non_blocking=True),center=False)
print(res)

Setting the default type to float16 might most likely cause other errors, e.g.:
input = torch.randn(100).to(device)

will also cause an error:

RuntimeError: th_normal not supported on CPUType for Half