Can excellent tubes transcend modest amps?

there is no definitive answer to the question posed by kanuk. until the criterion of "better sound" is denoted, the best course of action is to listen to an assortment of tubes, where there are return privilegs , to determine ifsonic improvements can be attained.

there is a risk when buying another amp, just as there is a risk of dissatisfaction when changing tubes.

our hobby is based upon subjective evaluation, personal preference and a lack of predictability.

it is best to be an empiricist without preconceptions.
without the facility to listen to alternatives, one is left with speculation and risk.

I will add my voice to the chorus of answers above. The answer is NO! The sound from your amp is the sum of its parts. I think tube rolling has acquired prominence because it is the easiest part to tweak. After all, you're not going to be changing the output transformer in a hurry, are you?

I agree with the posts above which say that good tubes will make an improvement, but, a better overall quality of the amp will make the superior quality of better tubes even more evident. To me, the biggest determinant of quality is the output transformer, a part which also happens to be the most expensive.

Any particular preference would depend on a variety of factors, such as personal preference, system matching, etc., so experimentation is the only reliable approach to finding the right tubes. It could be NOS, it could be new tubes, it could be "cheap" tubes that will float your boat. It is hard to generalize.

In my system, I generally favor older tubes to current production, but, there are some current production tubes that are very good too. For example,I like EML meshplate 2a3 triode output tubes, but, they seem to be reliable only in amps that run them gently. Small signal tubes have even more distinct personality in my amps; I just happen to favor Tungsol roundplate 6SN7s and Telefunken ECC803S (apparently others like these too, as they are very pricey).

While I agree with a "no, not in general", I have a first-hand experience with doing exacting that: spend almost as much in tube upgrade as in the original price of the equipment. I bought a Yaqin MS12-B preamp for $200 and while decent with stock tubes, I felt the urge to upgrade to Mullard Platinum and other goodies for about $150. Result: spectacular, both as a phono and a line stage, truly mesmerizing and competing-kicking ass with some well-regarded preamp costing up to 5 times my total final cost which are noisier when they are not inferior sounding to mine.

Behmene- Kudos on not heeding the(never having tried it) nay-sayers!