18Watt.com

These have the Sovtek name opn them, but I wonder if they are actually different than the standard stuff from Sovtek?

One of them claims to be hand picked...

Is there a perferred stage to use them in the 18w?

Zip

They are just tested Sovteks (the Rs) or Chinese (the Cs). They are more expensive than just buying the same thing with a Sovtek or Shuguang label. But you do get a warranty.

I've stopped buying Groove tubes for preamp tubes and have had very few bad tubes. I've also had some duds from GT.

I think the real reason to buy GT is just for the warranty or if it is all you can get.

Hand picked? I guess that means they actually test it and it is within certain specs.

I do repair work for a local music store and I have had issues with the "R" type being really bad noisy, they hiss like there is no tomorrow. The "c" type are a little bright for my taste but work well.

I just think that Groove Tubes are over-hyped for what they really are. Well tested, but otherwise not very special tubes. GT buy cheap tubes in bulk, then test them and throw away the bad ones. There's lots of better sounding stuff around these days IMO.

Just to pile on a little more, I've found places like the Mojo Musical, Tube Store and Tube Depot do pretty decent testing, so for preamp tubes there's no need to spend a lot of extra $$$ on GT.

I also feel the same way about power tubes. I do like to buy matched power tubes (not a requirement, but a preference), so that they wear evenly and I know when they do start to drift that they'll still be pretty close. That's the dirty secret about "matched" tubes. The match will only last for so long and the tubes will drift out of match. Some brands stay closer than others...