The Quicksilver V4's are flexible in tube choices to tailor the sound. Hand made in the U.S.A and built to last. I would not describe them as overly warm, but if you want a creamy mid range you could go in that direction with a tube that has that characteristic. They can also use the KT 120 which is supposedly very nice in those amps. I use the JJ KT88's and find them to be very nice. Mike Sanders uses them as his premium tubes in those amps.
All of the amps mentioned by other posters would be worth auditioning. It's all a matter of system matching and taste. Good hunting.
All of the amps mentioned by other posters would be worth auditioning. It's all a matter of system matching and taste. Good hunting.