The tubes plays a significant factor, but Its not only the tubes, but the design and all the parts in the tube amplifier makes its own contribution to the sound of the amplifier, otherwise all the amplifiers would all be the same and the tubes brand and model would be the deciding factor.
If i were to go back to tubes, I would go with Cayin, I had the Class A version of the A-70T before, the design is solid and the craftmanship is outstanding. The only thing i dont like about the Cayin and the other tube brands is the tubes installed. If you can buy the amp without the tubes, go for it and get better tubes, its night and day difference.