What do S4A tubes bring sound-wise in a phono preamp or tube preamp?

Especially in phono preamps and sensitive tube preamplifiers, particularly low-noise, low-microphonic, low-distortion and low-hum tubes are important. That is exactly why S4A tubes are often especially interesting here: they are very well suited for applications where a lot of gain is required and, at the same time, quietness, stability and clean reproduction are crucial. Especially in phono stages, a carefully selected tube can bring more sound quality than a simple standard replacement, because even small differences in noise, microphonics and matching become clearly audible. This applies, for example, to popular units such as the Pro-Ject Tube Box DS2 and Tube Box DS3 B, which Pro-Ject explicitly positions as tube phono preamplifiers, or to classics such as the EAR Yoshino 834P. Models such as the PrimaLuna EVO 100 Tube Phono Preamplifier or Manley Oasis also show how important a clean tube stage is in high-quality phono preamps for noise behavior, dynamics and fine resolution.