The NOS Brimar CV4003 has a moderate amount of warmth with extension up top and in the bass. Not as warm as Mullard, but is more detailed. I’ve used them in preamp gain stages and also in my amps.
Brent Jesse is a great dealer, but the CV4003s from Upscale are low noise and have lasted for years. Just so there's no confusion with other tubes, these have box-plates.