One of the best ways to do biamping is using identical amps in a vertical configuration (one amp for each speaker) with an external crossover bypassing the speaker’s internal crossover. See this diagram:
With the Creek 100p, you would have identical amps, however the only option is horizontal configuration (one amp for high L&R and one amp for low L&R)using the speaker’s internal crossover. Even using the speaker’s internal crossover, it is still best do a vertical configuration. IMHO, I choose option 2, but not a tube amp. Looking at Stereophile’s measurements of the PSB Imagine T2, it doesn’t appear tube friendly with the phase angle and impedance issues. Tube amps work best with a benign load. If you want tubes in your system, then anywhere except power amp.