Tube swapping in amps and preamps

Hello fellow audiophiles,
What is the difference in effect between swapping tubes in a power amp and a preamp? Should you do both,or,one or the other?
Put the best tubes you can in both. What "best" means will depend on your preferences, system synergy, and budget. I have found NO components that couldn't be improved by exceptional NOS tubes. Some new production tubes are quite good but almost none can match the best of the best when tubes were king... (recent WE excluded IMO).
Here's a thought, perhaps you should do neither! Pre amp tubes, amp drivers and power tubes all contribute substantially, and probably equally, to the sounds you hear. You need to decide what you want to change, sound wise. The sound you want to hear will determine your selection. Personally, I would start with my pre-amp and if that didn't give me what I wanted I'd start working on the amp, starting with the drivers. Leave the power tubes til last (due to the expense involved - but if you have smaller power tubes (read less expensive) you may have a couple sets of new production tubes about for contrast purposes). There are new production tubes that work well in amps but not so well in pre-amps. There are NOS tubes of moderate price that can work as well in either and there is some dreck. Then there is the expensive NOS stuff, which should be approached with caution, unless you are absolutely sure it will work well in your application. Usually its not a matter of "tube A" being better or worse than "tube B" its about how the tube will compliment your unit and your system and give you the sound you want to hear. Caveat emptor.
I'd agree to some extent with Jwaugh's statement regarding NOS tubes. I would add that there are some instances where current production is close enough to NOT warrant the very significant added cost of NOS, not to mention risk if you are not buying from a known seller. There are plenty of boutique tubes available in the big bottle triode category that are current production, though are just as expensive as NOS.

Given the choice between spending $ 100/tube on some GEC KT88's or pick up a quad of JJ Teslas for just a bit more than one GEC might cost, I'd prefer to spend the extra money otherwise as opposed to the marginal improvement the GEC's might render. Same goes for Mullard EL34's. Svetlana's brand new 300B tube is supposed to equal if not surpass the WE according to the Stereophile shootout (as reported in a follow-up). Sovtek's 2A3's are excellent tubes in that category. I just had some vintage Sylvania's (the good ones) to roll against them, and though marginally better in most areas, I didn't feel they were worth the added cost in my PP 2A3 amps...perhaps in the SET amp I compared them on. NOS construction and materials may have a leg up on most current production tubes, but I think each person should weigh the cost to the (degree of) benefit. I've heard bigger gains by improving the tubes in a preamp section than I have in swapping the tubes in amps, but I don't think this is a rule by any means. You may want to list your pre and amp and the tubes you are using and state what you are considering changing/investing.

I've been swapping for weeks now in my AI M3A and all I can say is, "Buy as many well-reviewed tubes as you can and start swapping" 'cause most have a distinct sound. Plus, it's really fun.
Hehehe... I understand Marco's point - which incidentally is what I meant by the comment that some types of current production tubes are quite good. Perhaps that applies most to some boutique tubes.

In general, the gap on power tubes is less apparent as well, that much also I would agree with readily. I had to reply about the GEC example, though, since that one hits home for me. I desperately wish the gold monarchs weren't as big a leap as they were in the two KT88 amps I've used... I now own two octets of GEC gold monarchs (may sell one now that I only need 8 instead of 12). I would LOVE to sell mine and put the cash into something else, but A/B comparisons - even with that listening bias - just won't allow me to do so... I have tried a LOT of other KT88s too. I dunno. I found the same with the metal base 6sn7s as well. Perspectives on cost-return must be even more variable an analysis in audio than sound quality is. Later degrees in improvement sometimes just seem to cost so much more than the early leaps in everything performance-related.

Now of course I'm going to contradict the perspective I just pitched...

Not going to touch the comment about Svetlana vs WE 300Bs except to ask what 300B you liked the best, Marco? I mostly ask because I'm curious; I liked several of the new production 300Bs immensely - KR 300BXLS and a couple of the meshplates in particular seemed to do so much right. Of course I was taking $$$ into account for the 8 300Bs I needed and decided in that case that the returns were just not worth the extra cash. Don't worry, I apply the same inconsistencey to cars and every other hobby I have too! ;)

Also, Newbee gave what sounds like very good advice to me - starting on the earlier gain stages (i.e. DAC and preamp) will give you the highest bang for the buck in almost all rigs.
I use WE 300B's and have not tried the new Svet's. As I said, I was only reporting a shootout/review that you can find in the StereoFool archives. In my SET amps I've only tried the WE's, some Chinese (not unlistenable, but in comparison to WE's an entire world away), and a pair of EH 300B's...not bad overall, but just did not have the mid-magic vocals realism of the WE's and had a kind of edginess to them in the highs in comparison. As I recall the WE's just seemed more balanced too. I am very happy with the way the WE's sound so have not found the need to roll those tubes, perhaps much like your conclusion with your GEC KT88's. If money were no object to me, I'd roll away, and go for the best available tubes overall. But our money tree is very small, hence the cautionary point of view that one should weigh their priorities and investment against diminishing gains. In the case of the KT88's $300 buys a whole lot of music...well, gosh, I guess these days it'll get you a few CD's anyway!

Good input from everyone here, IMO.


PS Have you rolled your GEC's against the JJ Tesla's? I ask because I did that with a pair Quicksilver Silver 90 (pentode) amps and could not hear much of a difference to my ears. I don't think the tubes were Gold Monarchs though (at least I don't recall them being those, but this was years ago).
Nice choice Marco! I wish I could have run an octet of WEs but just couldn't... I did try the JJ Teslas as one of the A/Bs and made sure they were optimally broken in. I have never tried any other GECs, so that may well be the difference - I dunno. BTW - NICE setup you've got!

Best of luck Johnny7 and have fun!