History

Equipment:

- Mark Levinson No.32 preamp
- B&W 801 speakers (8 ohm)
- Totem Acoustic Model 1 Signature (4ohm)
- Rega Planar 5 turntable with a Dynavector MC cartridge
- Krell SACD player.

Cables:

- Speakers: 15' Monster XP Clear Jacket, AWG 12
- Audio: 3' Monster RCA Stereo Audio 300

There were four subjects (myself included, call them A, B, C, D) Each had a chance to bring his own selection of music on CD, SACD or Vinyl. It happened that two of the subjects were into the Classic genre, one into Jazz/Pop and one into Rock/Avantgarde. Here's the selection:

Classic
- Beethoven, Symphony No. 9 by Hans Sotin, Ludwig van Beethoven, Georg Solti, Chicago Symphony Orchestra & Chorus, CD, 1995
- Mozart, Violin Concertos, Julia Fischer, Yakov Kreizberg, and Netherlands Chamber Orchestra, Hybrid SACD, 2005

Jazz/Pop
- "Friday Night in San Francisco", Al Di Meola, John Mclaughlin, and Paco De Lucia, Vinyl, Live 1981
- "Live in Paris", Diana Krall, CD, Live 2002
- "Time Out", Paul Desmond and Dave Brubeck, SACD, 1999

Rock/Avantgarde:
- "Starless and Bible Black", King Crimson, Vinyl, 1974
- "The Seduction of Claude Debussy", The Art of Noise, CD, 1999
- "Up", Peter Gabriel, Hybrid SACD, 2003

Each of the subjects were interviewed on the best known power amp experience:

A - Musical Fidelity Tri-Vista kW Monobloc
B - Halcro DM58
C - McIntosh MC1201 Monoblock
D - Mark Levinson No.333

I would start with a personal satisfaction: I am not deaf (yet!). My first estimate of the sound (before the amp was installed in the chassis), as described in the web site's conclusions, were mostly confirmed.

It was unanimous that this amp is the most unforgiven piece of equipment that was ever heard. Everything, the slightest noise in the recording, background foot stomps during live performances, everything that was (probably) not intended to be listened at is there in the speakers. If this is good or bad, it is questionable. Two of the subjects characterized this behaviour as "tiresome", "distracting", "aggressive", the other two subjects mentioned "extremely detailed", "precise" and "very involving". Further discussions revealed that it's ultimately a matter of expectations. Some subjects are expecting from an amp to hide most of the background details (typically in live performances), a less grippy, authoritative and a bit softer sound, with less overall impact and dynamics. Others think that listening to a recording should be an integrated experience, so every detail is revealing and important.

During the first morning session, two of the subjects identified a faint harshness in the treble response. It took me some time to identify/hear this effect (it appeared to be more evident on tracks with very high dynamic like King Crimson's "Providence"). Strangely enough, it was located in the right channel only. When everybody went for lunch, I popped the case lid and took another look... and sure as hell, the right channel OPS had lower compensation caps (33pF/22pF instead of 47pF/39pF). I replaced the caps and the afternoon session showed that the harshness was gone.

Everybody agreed that the PGP amp has a very high harmonic accuracy. Compared to each reference amp experience, the PGP amp was excellent in preserving the distinctive timbres of voices and musical instruments. On Mozart's Violin Concertos, violins were sounding like violins, without any "synthesized" or "electronic" timbre.

The PGP delivered an amazing midband: not "euphonic", or "glazed-over", but "natural", with "unforced detail" and "sweetness". The voice on Diana Krall's "Live in Paris" sounded "grain-free" and "extended".

Dynamic was another very strong point. We were unable to hear high-level congestions, or any other limitations in dynamic range.

Once the OPS compensation was fixed, the trebles were stunning. "Friday Night in San Francisco" acoustic guitars were "tangible", with an intimate touch to the sound. In fact, all live recordings sounded suprisingly fresh, with a sense of involving never heard before.

The bass response was found as "deep", "tight", "tuneful", "thunderous dynamic", and "snappy". The Art of Noise's "Born on a Sunday" sounded "involving" and "captivating". The full palette of tonal colors were so well rendered they were "physically sensed in our chests".

Results in the 4ohm speakers were dissapointing. To make a long(ish) story short, the PGP is unable to properly drive 4ohm speakers up to it's full power of 200W/ch. The PGP OPS deliveres and estimated of 15A peak and that's definitely not enough to drive 4 ohm speakers (dipping at 2 ohm, plus the phase lag) at full power. However, up to about 100W/channel, the 4 ohm performance is comparable with the 8 ohm load performance. One to another, my conclusion is that lateral MOSFETs are not recommended for the ultimate performance in 4 ohm speaker loads. A good lesson for the "lesson learned" phase of this project.

More to come...