Integrated Amplifiers

Pass Labs INT-30A Pure Class A Integrated Stereo Amplifier


In Use

I tested the INT-150 using an OPPO BDP-95 universal player, Carver Mark IV ribbon speakers, and Krix Equinox Mini-Monitor (Bookshelf) speakers. Cables were Wireworld and Emotiva.

The first thing I did was listen to several albums with the Krix speakers, including the albums that I used with the INT-150. Then, I played several mono music tracks that I had created by ripping the CDs to my computer, and then, using Adobe Audition CS6, I converted the stereo to mono. I set the system up with the INT-150 driving one speaker, and the INT-30A driving the other, and just muted one speaker when listening to the other by using the remote control (I placed the amplifiers close to the speakers so the remote wouldn't mute both channels when I pushed the Mute button). After a while, I switched the speakers that each amplifier was driving. To calibrate the sound, I used a 1 kHz sine wave and adjusted the volume control on each amplifier so that the SPL coming from both speakers was the same (80 dB at 1 foot).

Artur Rubenstein was a living legend, and fortunately, he lived a long time and recorded an entire library of music. Piano is a difficult instrument to reproduce, but the INT-30A had no problems here. I could only hear the deep fundamentals of the lowest notes on the Carver speakers, but they are not very sensitive, so loudness was more in the domain of the INT-150's capability. Nevertheless, at "normal" listening levels, where less than 10 watts are used, the INT-30A and ribbon speakers were a wonderful combination. In the INT-150/INT-30A left/right channel mono test, I could tell there was something different between the two amplifiers, but I could not describe what it was, yet. They both sounded very good, but there was a voice in the back of my mind telling me that they differed. This album is The Chopin Ballades & Scherzos (RCA Red Seal 82876-61396-2 RE1), which is a remaster in SACD three-channel, with the CD version included.



Here is an SACD recording of Liszt Organ Works (Membran International 4-019272-601446). Again both Pass models sounded terrific, but it strained the INT-30A, while the INT-150 was able to deal with it, at reasonably loud levels. However, when I set it so that the deep pedal tones didn't use more than about 25 watts, even the Carver Amazings shuddered when they were driven with the INT-30A. With this recording, and the INT-150/INT-30A left/right channel mono test, I could not hear any difference between the two amplifiers.



Playing this Recorder Sonatas CD (NAXOS 8.572023), which included a recorder (similar to a flute), harpsichord, and cello, I discovered what the difference was between the two Pass models. There was just a bit more clarity and detail in the INT-30A. I had originally expected that there might be more warmth to the INT-30A, but this was not the case. It was simply in the details. Now, I would be happy with either the INT-150 or the INT-30A, but if I had the INT-30A, I would pair it with much more sensitive speakers, such as horn designs, which have a sensitivity approaching 100 dB/w/m.