[50jess]

If I connect an external preamp to a tube integrated amp, will the external preamp bypass the preamp section of the tube integrated amp and render the preamp tubes (using NOS tubes) of the tube integrated amp useless? 

[decal]

It depends on the design of the integrated, check your manual to see if your amp has this feature. My Rogue Audio Tempest can be configured as a power amp only. If you don't have a manual, you should really contact the manufacturer and ask them.