This dual-SID tune expects a 6581 at $d400 and an 8580 at $d500.

The current version of VICE can't emulate two different SID chips. You can
still run the program on a machine with two 8580 chips, but it won't sound as
intended. Select mono output (-soundoutput 1) to mix the output from both
chips:

x64sc -sidextra 1 -sid2address 0xd500 -soundoutput 1 lft-overflow-2sid.prg
