In exclusive partnership with top-tier modification house Parts ConneXion, Underwood HiFi is proud to offer the following carefully tested, factory-authorized performance enhancement packages for the Marsh P-2000t tube preamplifier.


By virtue of selling consumer-direct, we can offer these super-charged, brand-new models for $410 less than the same modifications would cost retro-fitted - though we offer that, too.

We are glad to introduce our fully modified Marsh P-2000t tube preamplifier. The stock unit has received excellent reviews and is a wonderful preamp at its $1500 retail price. Our mod takes this preamp to a new level to become a bona fide world-class performer. Fully modified, it now competes with any $5000 or $6000 preamp we know of. The mod was designed by Chris Johnson, the founder and former president of Sonic Frontiers.

P-2000t Level-1 mod - $2,290 + shipping ($1,200 retro-fit)

Our Level-1 mod installs:

  • Four 'small 'EAR brand Sorbothane isolation feet
  • Two sheets of SoundCoat chassis damping material cut & applied where applicable
  • Two pairs of Vampire CM-1F/CB copper body, direct gold-plated RCA input jacks
  • Four Auricap signal-path metalized polypropylene power supply bypass capacitors
  • Two TRT DynamiCap metalized polypropylene coupling capacitors
  • Two REL-Cap TFT Teflon coupling cap bypass capacitors
  • Two Black Gate power supply capacitors
  • Fourteen Audio Note ½ watt Tantalum film resistors
  • Five feet of DH Labs Revelation Series pure 99.99% silver Teflon-insulated input/output wire as well as 5 feet of Kimber TCSS hyper-pure copper hookup wire.
  • Four International Rectifier Hexfred ultra-fast soft recovery diodes in the power supply
  • Two New-Old-Stock RCA blackplate 5687 vacuum tubes as well as Pearl Tube Coolers to extend life and reduce microphonic.
  • A high precision ultra smooth TKD conductive plastic volume potentiometer.
  • We then lower the gain from 23dB to 14dB for more useful volume range
  • TRT WonderSolder used throughout.

Sonic changes of our Level-1 mod

  • The preamp's innate noise floor is much lower, producing blacker silences and resolving more low-level detail with better ambiance retrieval.
  • Three-dimensionality and soundstaging is improved.
  • Transparency is greatly improved, as though a slight veil over the music has been removed and one can now look deeper into the soundstage.
  • The preamp is smoother in the midrange while remaining very detailed.
  • It also became more dynamic and seems to play louder, with heightened dynamic contrasts.
  • Imaging is better defined and the soundstage is much larger, both in width and depth
  • The bass is improved. Low bass is fuller, with more weight and authority, while the midbass has more punch and attack.
  • The modified unit is now an uncompromised performer and fully capable of playing with the Big Boys at multiples of its own modest price.

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