I have a Unison Research S2K.
The valves will need replacing very soon,(x2 KT88-SOVTEK, x2 ECC82-PHILIPS)Replace with the same makes or . . . ?
Thanks, JOHN.

NOS KT88 are very expensive for the good ones. I think Gold Lion (can't remember if this was manufactured by GEC or Marconi) would be the dream if you can afford it (might cost more than your amp) but Sovtek may not be a bad choice. I would probably ask Derek Rocco at www.watfordvalves.com to see what he thinks.

On the ECC82 front, less expensive and you've got lots of choice. It's probably a good position to try several different ones to see what's to your taste. British or Dutch manufactured Mullards are always the top choice followed by Telefunken although Philips are excellent. Mullard was actually a subsidiary of Philips for most of it's existence.

Be aware though that the modern Mullards are infact Sovtek.

Obviously, I've got no commercial links with Watford.

Nice one, I will contact Watford valves