When choosing tubes, for a pre or phono section; it's
imperative to seek out those that are tested, and certified,
for that purpose(Low Noise). Of course; your provider has to
know how to properly screen valves. ie: Upscale Audio (
https://www.upscaleaudio.com/pages/Testing-Small-Signal-
Tubes.html ) However; when you crank your volume to full,
the pre might not only let you hear tube microphonics, but
anything that interconnects, or empty inputs, may be picking
up(ie: EMI/RFI). If there's a phono section ahead of it;
it's noise is amplified/compounded.
imperative to seek out those that are tested, and certified,
for that purpose(Low Noise). Of course; your provider has to
know how to properly screen valves. ie: Upscale Audio (
https://www.upscaleaudio.com/pages/Testing-Small-Signal-
Tubes.html ) However; when you crank your volume to full,
the pre might not only let you hear tube microphonics, but
anything that interconnects, or empty inputs, may be picking
up(ie: EMI/RFI). If there's a phono section ahead of it;
it's noise is amplified/compounded.