Today I compared three preamps in my system. All other components were the say except interconnects which were different but comparable quality.
  1. Sonic Frontiers Line 1 tube. This is generally considered very neutral for a tube preamp. For the unit plus some tubes I rolled, including shipping, etc., I paid >$1400; (the last MSRP was $3500).
  2. Hafler DH-100 s/s from the late '70; this unit modified by replacing all capacitors in the signal path and most in the power supply, and replacing the original 5532-type opamps with OPA2134's. Total cost to me ~$190.
  3. ALPS 'Blue Velvet' potentiometer plus input & output connectors and minor hardware -- i.e. a minimal passive preamp. Total cost <$60.
My listening observations:
  • The Hafler and ALPS passive were extremely close. Both were clean, detailed, neutral, and dynamic. I had the impression that the passive had very slightly tighter bass, and maybe very, very slightly better detail.
  • The Sonic Frontiers was similarly clean, detailed, neutral, and dynamic; the bass was, if anything, closer to the ALPS passive. Where the SF was clearly, (i.e. not subtly), "superior" was in soundstage depth.
Assuming the observations are accurate, (you have only my word for it), can general conclusions be drawn?
  1. Tentatively that the commonly-ascribed tube characteristic of depth, (sometimes described as greater presence, palpability, or realism), is in fact an artifact. Of course, based only on such limited observations of my own, and hear-say from other audiophiles, the hypothesis is strictly putative.
  2. You might not have to spend thousands on a preamp.