You can convert your AddmusicK 1.0.X SPC back into MML and BRR samples.
Select your SPC file and press Start, then the disassembled result will be downloaded automatically from your browser.
Only AddmusicK 1.0.X SPC is supported. For AddMusic 4.05/M/etc SPC, use NintSPC.
This tool is purely frontend-based, which won't upload any data into our server. You can get source code here.