Tubes for VTL S200

I had an awful experience with an S400. I bought tested, aftermarket tubes from reputable resellers because the original VTL tubes (6550s) that came with the amplifier got nowhere near the 'advertised' (website) and in the S400 manual, 'average' life of 3,000 hours. And they were twice the price. The aftermarket tubes were slightly but not much better in terms of reliability. Thinking this was an amplifier issue the local distributor went back and forth with VTL who insisted that only VTL tubes be used. I bought a matched set (12x KT88s) only to have 8x of them fail in less than 1500 hours.

The KT88s were more detailed and dynamic but less 'flesh-on-the-bone' compared to the 6550s.

I sold the S400 and note VTL removed statements on their website referring to their autobias function delivering the 3,000 hours average.

If you don't mind VTL not offering support because you're not using their tubes, then go for it!

YMMV.

That’s pretty interesting and terribly discouraging. Especially being that in a review I read where, and I might be getting this wrong, VTL offered an upgrade in tubes(maybe kt 88s?) for an extra $400 with the S200.

I just purchased GL KT88s. I hope I didn't make a huge mistake.

I don't think you made a mistake. The GL KT88s are normally pretty robust. Each brand has a different sonic character though. All the VTL amps run the tubes pretty hard. You may want to buy a few spare KT88s in case you get a failure or two. 

You may want to measure the B+ on your amp. Would guess its somewhere between 550 and 580VDC.  

If you buy tubes from VTL they pre-screen them at the higher working voltages on their burn in fixture to weed out weaker tubes. If you don't want to pay for this, then you may want to order a few spares form normal tube dealers to have laying around. 

Stick with the Russian KT88s or 6550s and avoid all the Chinese versions unless you like tube fireworks. 

Thank you! 

I bought them from Sweetwater but haven’t gotten them yet. I like the S200 very much but feel that with other tubes it can sound even better.

Also looking for black plates. Should all 4 be same model and brand? Or two and two?

NP.

Have not purchased tubes from Sweetwater so no idea on what type of testing they may or may not do. 

As for input tubes you may want to look for either UOS or NOS Raytheon, RCA or sylvania black plate 12AT7s or 12BH7s (on the current model of S200). Depending on which version of S200 you have the first tube will likely be a 12AT7 but the 2nd tube can vary. 

The tubes don't have to be the same brand. 

When buying older tubes just be sure to clean the pins. Any pin oxidation can lead to noise. 

If you are still using the factory installed input tubes, they were usually JJ. They are ok but not the greatest.