PS Audio BHK Signature 300 Mono Power Amplifier

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Equipment report
Solid-state power amplifiers
PS Audio BHK Signature 300
PS Audio BHK Signature 300 Mono Power Amplifier

The Signature 300s were equally excellent with the best modern digital recordings that place similar emphasis on musical life and a natural soundstage, such as those by experts like Peter McGrath or ones that you find on the 4L and Channel Classics Labels. These were exceptional in providing depth with chamber music and choral performances that I’d heard live while the digital recording was being actually being made. As for natural image size and placement, centerfill, and soundstage width, the BHK Signature 300s do as well as any amplifiers I’ve heard at any price. As stated earlier, the limits are not set by the power amplifier; they are set by the way the recording was miked and produced, by the need to use only two speakers, and by the other components.

Moreover, this soundstage excellence is consistent on both solo instruments and voice, and small chamber and jazz groups. Indeed, these amps test the soundstage limits of the best large jazz band, symphonic, and operatic recordings. No recording in a high-end system in a real-world home is going to sound exactly like a live performance of a full jazz band, grand opera, or Mahler symphonic spectacular in a real hall. The BHK Signature 300s do, however, come as close to putting you in Row D to Row K as the recording will allow. Once again, I’ve only heard a handful of power amps do as well—and all put you more in Row L to Row P.

Once the BHK Signature 300s are broken in, they also have an exceptionally natural timbre at any dynamic level throughout the entire frequency range. Some otherwise excellent amps lack the ultimate in “grunt” and power in the deep bass. Others seem to be voiced to slightly emphasize musical detail with either a bit too much energy in the upper midrange, or a bit too little energy in the upper bass and lower midrange. The BHK Signature 300 gets it as right as the rest of your components will permit, and has by far the most natural timbre of any PS Audio amplifier I have ever heard.

I can’t speak to the degree to which having Paul McGowan and Arnie Nudell working with Bascom H. King in the listening phase led to this excellence, but Paul’s sudden conversion to vacuum-tube drive stages does seem to have come in part from this collective effort. It has really made a difference. Just listen to a really great recording that emphasizes the violin, the full range of the grand piano, percussion detail, or mixes of male and female voice (especially soprano). Timbre may not be king in voicing high-end gear, but it is absolutely critical.

The same excellence applies to musical dynamics and contrasts, air, and fine musical detail. One aspect of power amplifiers that has always puzzled me is the number of high-power amplifiers that can produce very high dynamic peaks, but lack the dynamic life and natural energy of better amps with far less rated power. Part of this difference almost certainly comes from the fact that most acoustic music depends on low-level detail, dynamics, and air, but this clearly is only part of the story. Being able to handle high SPLs doesn’t prevent some amplifiers from lacking life and natural musical realism—even in the parts of the music that are really loud.

You won’t have any such problems with the BHK Signature 300s. Like other truly excellent power amplifiers, they seem to perform almost effortlessly, and often transparently. You hear the compromises in the recording rather than the limits of the amplifier—whether you are listening to a song cycle, solo instrument, or the most demanding passages in music such as Saint-Saëns’ Third Symphony. One of my friends who plays bass guitar loves the BHK Signature 300s, and so does another friend who is an opera buff, and both stress the natural life they bring to the sound.

Interface and System Compatibility
The BHK Signature 300 should be an outstanding performer in virtually any system I can think of, with the possible exception of extremely efficient horn systems with limited tolerance for power. These amps are truly powerful.

They certainly are not particularly sensitive to speaker load, or to a particular brand or model of speaker cable or interconnect. You will, however, hear the colorations and nuances of your speaker cable and interconnects more clearly simply because this amplifier—like all of its best competitors—is more revealing. One of the key tests of a great component is that it reveals the rest of your system’s colorations. This was not a problem with my best AudioQuest, Kimber, and Transparent Audio cables, but I could hear the differences between them in ways that only emerge with really good amps.

The only caution I would give you about setup is that the BHK Signature 300s deserve good AC power input and power cables, and that you may have to change some of your other components to fully hear how superb this amplifier really is. You are going to want your other components to be worthy of such illustrious company.

Summing Up
A truly excellent amplifier. Scarcely cheap, but less expensive than most of the amps that challenge it in quality—and the stereo version is half the price of the monoblocks. I’m not giving up the Pass Labs 160.8s, but I am putting a second reference system together, and I’m keeping the BHK Signature 300s. Two of the best power amplifiers around can be better than one.


Output power: 300W into 8 ohms, 600W into 4 ohms, 1000W into 2 ohms
Inputs: RCA (unbalanced), XLR (balanced)
Outputs: Two pairs of gold-plated copper binding posts
Gain: 30.5dB +/-0.5dB
Sensitivity: 1.2V
Noise: <-85dBV, 100Hz-20kHz
Input impedance: Unbalanced 100k ohms; balanced 200k ohms
Output impedance: <0.1 ohms
Frequency response: 10Hz–20kHz +/- 0.1dB; 10Hz–200kHz +0.1/-3.0dB
Dimensions: 17.1" x 8.7" x 14" chassis only; 15" deep including connectors
Weight: 83 lbs. each
Price: $14,998/pr.

4826 Sterling Drive
Boulder, CO 80301
(720) 406-8946