"A bit of noise is completley normal" ??

I have a high end integrated amplifier. The input (source)selector switch on my unit created some audible static when I switched sources. While I had the integrated at the manuf. for an upgrade, I asked them to check out the source selector switch. After I got my integrated back from the manuf. one of their reps replied:

A bit of noise when you switch from one input to another is completely normal. After all you are switching contacts. The switch is fine.

That does not ring true to me. Do you consider "a bit of noise" in a switch from switching contacts to be normal? It's not normal to me. For me it meant dust is in the switch. Not satisified with that response.
"I have a high end integrated amplifier."

Well. I'm not going to call YOU a liar, but I might have a few choice words for the manufacturers rep!

OK, yes, it's "normal" if:
The unit is over 10 years old and needs to have the switches and volume/balance controls cleaned.
It's a new unit however the manufacturer uses inexpensive parts which are "normally" noisy. But then it's not a "high end" unit, is it?!

And to prove my point further, many manufacturers (as you may have noticed) offer 'upgrades' to their "high end units" which usually invlolve more expensive volume controls and switches ;-)
You are right in believing that you were fed absolute ahhhhhhhhhhhhhhhhhhhhbullshit!

There may be some preamps that have noise associated with switching sources. These are called "noisy preamps with crappy switches." Acceptable only to those who buy into the crapola that your manuf. rep. tried to feed you.

If the switch used is not a type called 'make before break' (where the connection to the new position is made before the old position is released) then it is quite normal to hear a bit of a pop or click between positions.

However- in audio applications it is a standard practice to use a 'make before break' switch in volume controls and selectors.

Other things that can affect popping or noise in the switch:

RF from your sources (digital noise can do this too)
DC coming from a tube that has internal leakage or a short.

If a tube has some slight microphonics it can also ring or react slightly when the switch is moved. If this is the case moving the switch very slowly and deliberately will prove this out.
You forgot to disclose the rest of their reply!

"Given the time and resources required to diagnose this switch which in the end was not found to be faulty or a manufacturers defect, we will accomodate you this one time only by waving our usual $500 diagnostic fee.

As a courtesy, we therefore enclose an invoice for only $300 in addition to your $2000 upgrade charge.

Please note the limited warrantee associated with your upgrade is a generous 90 days.

Please allow at least 3 months for burn in before fulling appreciating the dramatic benefits of your upgrade."