Amp biasing question

I think what you are asking is really whether signal should be playing when you are measuring and adjusting bias (" biasing should be done with no input from the preamp").  I only check bias after the amps have warmed up for at least 45 minutes with signal playing to get the amps to normal operating parameters. That means the preamp/sources are connected, but when I check bias, I mute the preamp and no signal is passing into the amps when the meter is applied. Does that make sense?

I believe what you meant to say is that amp tube biasing should be done with the speakers connected.  It doesn’t matter is the preamp is on or off as long as it is not passing a signal. 

@whart  and @testpilot 

I understand what you are saying.  My question was due to reading separate threads that: if I was understanding them correctly, were stating that prior to turning an amp on, not only should it be connected to speakers, but the preamp should be turned on first (and shutting the system down should be done in the same order--amp off first and then preamp)

AND

that (again, if I was understanding correctly) that biasing should be done with the preamp turned off.  Perhaps that was what I misunderstood and what was meant was that no signal should be being sent from pre when biasing. 

Yeah, the turn on/off sequence is mainly to avoid a nasty "pop" noise from preamp turn on or off going through the system. You got it, @immatthewj 

Separate issue from biasing in my book. 

@whart  , yes, I agree that is separate from biasing.  And I may have misunderstood the postings I have been referring to.  I just was getting the impression that before turning the amp on, the pre should always be on.  If I had that right, one would have to have his or her preamp on while adjusting the bias.