Is upgrading stock tubes standard proceedure?

I've owned a BAT VK-D5 for the past 6 years, and the sound has changed markedly(although it's never sounded disappointing) with various tubes I've had in it(no simultanious system changes)!! That's exactly why I won't have it upgraded to the SE version(no tube rolling possible). I've got six Siemens CCa's(NOS two years ago) in it right now, and it's never sounded as lucid, accurate, open and with as much bass definition, extension and slam as it has with them. A system has to be able to resolve the changes that will be manifested by a tube swap in whatever component, and your ears have to be able to recognize/appreciate the differences. I've heard other manufacturers make unreasonable claims to dissuade people from experimenting with designs that they think are flawless. Probably lest the owner find out it can be improved upon.

Rodman99999, Sometimes I think Mr T is just being silly. Of course you can hear the sound of different tubes in the BAT. I do in mine, but I'll cede this to him, I don't hear near as much difference in the BAT as I do in my Raysonic where I think tube choice is critical. I have on one of the originals as well and have not had it upgraded. Very nice CDP I think. It does benefit from tubes with great clarity, as your Siemans. I tried some Bugleboys and it was a bit warm and fuzzy. Probably OK for someone looking for an antidote for a clinical system. :-)

Newbee- I've really been happy with my BAT since day one, and wouldn't trade it for anything but maybe the right Lector, or a Linn CD-12(yeah right!). The tubes are in a buffer circuit and, Yes- the piece can be flavored per someone's tastes. Personally: I've been striving for that last drop of transparency, ambience retrieval, bottom extention and definition. Between the tubes, and now a simple, home grown isolation system, I'm very satisfied. Kimber's KS-1130's didn't hurt anything either.

Generally speaking, it does not make sense for manufacturers to use anything but readily available current production tubes. First, they must be assured of adequate supplies for continued production as well as supplying customers with replacement tubes. Also, because each customer's system is different, and each customer has a different particular taste, a change in tube may not necessarily be better; so, why put a LOT of money into NOS tubes that may not be appreciated by the customer?

I know a lot of manufacturers don't encourage experimentation with different tubes. That is understandable given the sort of trouble inexperienced (or not-so-bright) customers can get into. Some supposedly "drop-in" alternatives for some types of tubes may really not be compatible in the particular circuit design even though the customer had no problem with making a similar switch in another component.

If the choice of tubes made by the manufacturer turns out to match YOUR own "ideal," that would be pure luck. Besides, you could not possibly know this without doing some experimentation. I own a pair of amplifiers that actually comes from the manufacturer with NOS tubes that are not cheap: RCA 5692 red base small signal tube, RCA double-plate 2a3s. I've talked to the manufacturer and he agrees that, even by his own personal taste, these are not the "ideal" tubes. He thought that NOS single-plate 2a3s sound better. But, they are very hard to obtain in near-new condition and are crazy expensive (about $2,000 a pair in decent condition, and I would need two pairs). It's not hard to see why the manufacturer would not consider supplying this amplifier with the "best" tube.

Are there current production tubes that sound as good or better than the best NOS? I don't know. I currently run EML meshplate 2a3s in my amp and like them MUCH more than the stock RCA double-plates. But, I have not had the chance to hear NOS single-plates in my amp. As for some other tube types, in my system, I have not found any current production tubes that I really like: for 6sn7s I like old Tungsol round-plates or the French Neotrons (copies of Tungsol round-plates); for 12AX7s I like Telefunken ECC83 or ECC803S.

Mr L- I've got a pair of the TungSol round plates, and a pair of Sylvania 6SN7W(tall bottle) in my Carys. Rest assured: You won't find anything current that can come close(or anything better, NOS). From that and the choice of Teles- You must appreciate an un-colored presentation of your music. I can understand the manufacturers having to use current production. Especially with the cost/lack of consistant supply of NOS tubes. Have you seen these?: (http://www.kraudioproducts.com/tubes/2A3blue/)