Pass Labs Mono Block Question

For the same reason , there are two of each / speaker for many speaker’s brand

One model of speaker cable better  for high frequencies      
One model of speaker cable  better for low  frequencies

From the Pass manual!

On the X1000 and X600 the two sets of output connectors on the rear panel are in parallel, for

the convenience of those who wish to bi-wire their loudspeakers. The red terminal is

connected directly to the other red terminal, and so with both black terminals

Thanks. 

Bi-wire or run shorter sp cables and use the terminals closest to the speaker.