...There are several line and connectors available to bypass the units preamp...
If by that you mean the integrated has jumpers and/or switches that provide an ability to make the integrated into a separable pre and power amp, like Nad and Creeks with their pre-out and main-in sockets, the answer is yes; folks often do this to take advantage of a good power amp section, bypassing a less good pre section.
If your integrated lacks this fuctionality, as Woodsyi says, you've still the sonic signature of the existing preamp section and might have additional gain from the inegrated's pre, limiting the range of adjustment with the added pre.
