KT88 s Sovtek vs Valve Art

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.