The Unison Research Unico has received countless kudos from reviewers and owners worldwide. This included our editor who thought highly enough of this terrific Italian hybrid integrated amplifier to bestow upon it the rarely issued Blue Moon Award as well as Best-Component-of-2002 recognition. But the twin subjects of today's writeup, the Underwood HiFi Level-1 and Level-2 Unicos, have had a little tinkering done under the hood to extract further performance gains. These modifications were executed courtesy of the Dynamic Duo of high-quality component modding, Parts Connexion's Chris Johnson and Underwood HiFi's Walter Liederman.


Rather than simply regurgitate the physical description of the stock unit, I urge you to point your browser to Srajan's review for the full skinny. The only overt external evidence of tweakery on my modded units was the replacement of one quartet of stock binding posts for WBT terminals, and the addition of a pair of Vampire RCA jacks for the CD input, connected to the main pcb via DH Labs Teflon tape-wrapped silver wire as used in DH's Revelation interconnects. It's on the inside where the real differences lie. The mods consist of the following:
Unico Level-1 mod: $1,890 + shipping ($650 + freight retro-fit)
  • Two sheets of SoundCoat chassis damping material to the inner chassis
  • 2 premium mil-spec, ultra low noise/microphony Mullard CV4003/12AU7 designed for 10,000-hour operation
  • Two Multicap PPFXS polypropylene film and tin foil inter-stage coupling capacitors
  • Two 1uf Auricap metallized polypropylene preamp input coupling capacitors
  • Twenty Japanese Riken 0.5- and 1-watt signal path carbon resistors with gold-plated leads
  • Two feet of DH Labs Revelation Series pure 99.999% silver solid-core input signal wire with Teflon tape-wrap dielectric
  • One pair of premium Vampire direct gold-over-copper-plated RCA female jacks
  • Four WBT 0763 single output binding posts
  • TRT WonderSolder used throughout
  • 4.5 hours labor

Unico Level-2 mod: $2,290 + shipping ($990 + freight retro-fit)

This modification adds the following over the Level-1 upgrades:

  • An extra sheet of Soundcoat chassis damping material
  • 8 Vishay-Telefunken SF4007 ultra-fast soft recovery diodes to rebuild two existing bridge rectifiers
  • 6 Black Gate electrolytic capacitors to the power supply
  • Two custom-made Burr-Brown OPA-627 opamp-based PCBs to dramatically upgrade the amp driver stage
  • Four large EAR Sorbothane isolation feet to further dampen the chassis
  • An extra 3 hours of labor for a total of 7.5 hours versus the 4.5 hours on the Level-1

Warranty is 90 days parts & labor on new modified units as well as on modifications performed on pre-owned units.
Concerned about the quality of third party modifications; a wee bit gun shy after learning of a few horror stories on sloppy workmanship? I can assure you that Chris and company perform such an immaculate job, you'd be hard pressed to differentiate their work from the original manufacturer's. Frankly, I'd trust Chris and Walter to mod my car. On second thought, that might not be such a good idea. I managed to blow up one of their Unicos. Somehow, I shorted out my speaker leads on the Level-2 Unico to immediately envision a pair of unsavory henchmen knocking on my door to rearrange my anatomy. Thankfully, that did not materialize. However, I fully expected to pay for the necessary repairs. Kindly, Walter and Chris saw fit not to issue a bill and informed me that a transistor and fuse had been the sole casualties. Whew!


I had read how many Unico owners discovered sonic benefits after disabling the speaker protection circuit via a pair of internal jumpers. After my little accident, I decided discretion would be the better part of valor and left those jumpers alone. According to Chris, modding the Unico is no task for the faint of heart. Major solder joints require breaking, including a very substantial one in the amp's back end. Rebuilding the Level-2 bridge rectifiers seems an especially complicated and delicate operation but Chris and Walter's belief that this affordable amp could reach a significantly higher plateau of performance justified addressing even challenging areas other mod firm might have conveniently avoided. The interior build quality of the stock Unico is quite good considering, but as always, subject to the obligatory concessions of targeting a particular price point. Chris' upgrades seek to alleviate said concessions by replacing key components with more upscale ones.


As I explained in my recent review of the Level-1 Music Hall Maverick SACD machine, judiciously modding an already exceptional component can net enormous performance gains for a relatively small premium that deftly avoids the standard 1:5 markup of build cost vs. retail. For example, while the actual parts cost increase of the Level-2 package might only set the original manufacturer back an additional $400, the compounded $2,000 would explode the stock retail of $1,595 to somewhere between $3-4K on the showroom floor - not the $2,295 Walter and Chris charge instead. A 40% savings? Not a bad deal, sez Candyman.

Both Unicos were leashed to my reference Meadowlark Kestrel 2s via JPS Labs Ultraconductors. Sources were the Level-1 Music Hall Maverick SACD and Rotel RCD-971 CD players, connected with JPS Labs Superconductor+ and Ultraconductor respectively. Blue Circle's BC86 Power Line Pillow and Wireworld Aurora III AC cables delivered purified AC while amplifier comparisons were made with my reference Bryston B60, and Song Audio's little sweetheart, the 4-watt SA-34 SB SET integrated. Don't expect either Unico to sound great out of the box. Both required at least two weeks of constant play before they opened up and started to boogie. Even if a stock unit were broken in before being modified, I'd expect facing a second break-in period. All those key component changes require time to settle in before reaching peak performance.



I won't be able to tell you how the modded units fair against the stocker. However, I can enlighten you about the differences I observed between the Level-1 and 2 versions. They were far from subtle.