Will improperly biased amp and preamp affect sound

Let me clarify; I'm talking about biasing the tubes.

If you do a search in the Audiogon discussion forums on the word 'bias' you will find even more than what will follow in this thread.

in my experience it depends on your setup (ie cables, tweeters,) ive owned amps which sounded great no problems, but did recently have a Jadis Orchestra Reference which made female vocals at high freqencies distort.

all in all, if it is easy to do, (ie biasing pots in handy places) do it....

ive owned amps which needed quite a bit more work than that and used my ear. you can also swap driver tubes from channel to channel

I would say that my experience is similar to Derrick's, my Cary 300B mono's distorted in the high frequency when the bias had wandered a bit. A quick and easy fix though. As far as preamps I've never had a preamp that needed to be biased so I can't comment there.

I wouldn't be so easy going about wrong bias. If the bias is too high, not only can you fry the tubes, you can also get a lot of distortion. If the bias is completely off, you may cause more damage than you like if the tube blows suddenly.
If the bias is too low, you will overwork the amp and will lack output.

I think if bias is too high you will burn up the tubes quicker than normal but, from what I remember, it should sound better than if it is biased too low in which it will sound boring and not involving.