None really other than flexibility in the future if you want to go with a different preamp or power amp.
It seems to me that the integrated might have two advantages, one very small and one more substantial:
1. As is, the integrated has shorter signal paths with no RCA jack/plug/plug/jack connection between preamp and power amp as well as no extra expense for the cables.
2. The B135 SST² is $1850 less expensive ($4695 USD compared to $6545 USD for the BP17/2.5B SST²)
Because the The B135 SST² has separable preamp and power amp sections, you still have the flexibility of going with a different preamp or power amp in the future. If the power amp gets upgraded, you also have a power amp section that could be used for zone amplification, bi-amplification, etc.
Steve
