Pardon me in advance for not answering your question directly, but I am concerned you may be wasting your money. I know you are looking for "the cheapest", but for me there are very significant differences between the KT88s around and you owe it to your Power 3s, let alone yourself, to tube them decently. The Svetlanas are way ahead of the Sovteks in a way that more than justifies the extra price. I have a set of the Sovteks that will probably never be used again. Ditto for the Golden Dragons. The minimum for acceptable KT88s in a good power amp in my pompous opinion is the JJ Tesla, a little more laid-back than the Svetlana, but I reckon the Svetlana will suit the character of the Power 3s better. I am sure others will have other favourites. I don't own any Valve Arts but something tells me they are Chinese valves (?). The only Chinese valves I have tried (from 3 different sources, or at least brands) each had a glassy upper mid that defeated the whole purpose of using valves rather than silly state. I hope this helps, I am concerned you do not waste your money learning this the hard way as I did.
Redkiwi has taken the time to give you the information that I should have offered. Not only is his assessment fair, my own experience has proven to be identical.
The only other thing I would add to this topic is the possibility of opting for NOS tubes. These are another whole quality level above all other, but certainly the most expensive way to go.
Not too much I can add to the other fine posts, except that I cannot emphasize how much better the old NOS MO Valve and Genalex Gold Lion/Gold Monarch KT 88 tubes are, at least in my equipment and my experience. They are terribly, terribly expensive, but they last FAR longer than any current make tubes I've used in my Jadis amps and are in a different class sonically. If you can find them at a reasonable price, and they are the real ones, they are the way to go (I know of a gentleman who claims to have gotten over 100 of them for a song from the Aberdeen, Md. tank proving grounds, where they were used in a tank vibration device--maybe we all can be so lucky!) . I recently acquired enough of them to last me till past where I can't hear any more, and I consider that to be one of the best investments I've made in years.
You really know how to make is suffer don't you, a lifetime supply of KT 88 MO valves?
I'll bet that next you are going to tell us that you audition these with Cameron Diaz, Sandra Bullock and Milla Jovovich.
thanks all, I will avoid the Sovteks and Valve arts and may opt for now, the JJ's and keep an eye out for the NOS stuff. Its just that 16 times NOS is getting up there in price.
Albert, you mention Milla, ever heard her solo LP? Great material and sonics, saw her live 3 times after hearing the LP. I must say she surprised me, I expected her to play on her looks but she was a true performer.
The tubes in the Power 3 are most likly Sovteks.Do you not like the sound of the amp.If the tubes are marked Sonic Frontiers then 95% sure they are branded Sovteks.
Albert, Cameron asked if she could come to the barbeque at your place?
Leafs, I love the sound of the amps. There are Svetlanas 6550 in there now.
Then the Sovteks would definitely be a let down. The Svetlana 6550 are nice tubes, and the one chance I had to compare them with the Svetlana KT88s showed the latter to be only marginally better.
I don't want to know about Genalex (etc) valves. Please don't tell me more. I still have to put two kids through University. No no no...
I would go with the Svetlana KT-88.I had Svetlana 6550 C in my Rogue 88.Nice tube.
Cameron Diaz prefers NOS KT-88's, but will settle for JJ KT-88 or Svetlana KT-88 or Svet 6550 ( in that order ) . Cameron wouldn't bet caught dead listening to Chinese or Sovtek tubes.
Redkiwi, the KT88s I got were my present to myself on having my son graduate from college. Had to do something with the money I'd otherwise be spending on tuition, you know! On Sovtek vs. Svetlana, I agree that the Svetlanas are the best of the 6550s currently available that I have heard, and would echo the above posters' recommendations. I do note that even they only lasted 1-1/2 years in my amps, where the MO Valve KT88s have gone almost 3 now with minimal wear. At this rate, my "lifetime" supply may last beyond that!
I find the JJ(Tesla/Teslovak) KT88 to be the best sounding of the currently produced KT88. I do not care much for 6550, preferring to instead go with KT88 if I am pursuing a sweeter tone, or Ei KT90 for a more neutral sound. One thing to be cautious about with the Czechoslovakian KT88 was that there was a period of time about two years ago where they were producing disastrous KT88. They would routinely fail within the first three months of operation. They had a difficult time maintaining consistent bias, and even sounded very, very erratic during operation. Russian tubes seem to represent a step down in sonics for me. But, if I was going to buy Russian tubes, I find Svetlana better to my ear.
I might put my JJ's back in and see if I agree. Difficult when I am in the middle of running in some cables so it will have to wait a week or so. Last time I compared them I preferred the Svetlana KT88 over the JJ, with the JJ being a little too polite. But this was a character thing not a quality thing.
I actually think we are on the same page Redkiwi. Just that our tastes, likes, and preferences may be different. The JJ/Tesla/Teslovak is a more polite KT88 in my experience. That is why I prefer it. Often, I like a classic tube sound if I am going to be using tubes. I guess the EL34 is the most characteristic of that sound, and the JJ KT88 can bring me closest to that. Other KT88/6550/KT90 may be considered more neutral, extended, or correct, but I cannot get over the realness and presence of the classic tube sound. Currently, my Jadis has the factory supplied Ei KT90. While many, many people feel this to be the most neutral, powerful, and best tube in terms of bass response of the big output tubes, I believe I will go to another tube(either JJ KT88 or JJ E34L) when it is time to retube. However, the process has been long in coming, as I can PERSONALLY vouch that the Ei KT90 lifespan seems to be tops in this league. I play the amp all the time, and the tubes show absolutely no sign of wear. In your case, a more forward tube might just be your ticket to happiness. But, if you do reinsert the JJ tubes, please submit your impressions. It would be nice if we could develop a "tube concensus" here on Audiogon, where everyone could simply come here and find the "probable" best tube for themselves the first time.