If one seeks a warmer, more romantic (colored) presentation from the typical tube amp, whether newer or older: try NOS tubes manufactured in Britain (ie: Mullard, Brimar, Genelex) especially in the amp's early stages.
For a sound somewhere between the cleanest and warmest: tubes from Holland and Belgium (ie: Amperex, Philips, etc) will generally do it.
For the more dedicated tweaker: change out resistors in the signal path, for noisier/warmer types, such as carbon composition.
Some of the oil-filled capacitors out there are quite warm, or: seek out NOS Black Cat types. They'll warm things up also, when used as coupling caps.
Lots of way to find a sound that sates your particular tastes, with a valve amp.