I confess, I'm a lifelong fan and owner of amplifiers built by Nelson Pass--going all the way back to his original company, Threshold, up to the present generation of Pass Labs amplifiers. It has been a real treat over the past two years to review the XA60.8 mono blocks (which I purchased) and the single-chassis X250.8 stereo amplifier. Historically, I have never auditioned any of the highly regarded Pass Labs integrated amplifiers. Therefore, it made good sense to me that my run of reviews on the Pass Labs .8 Series amplifiers would conclude with the company's brand new integrated amplifier, the Pass Labs INT-60, which retails for $9,000.
The INT-60 design is based on the hardware of a single-channel XA60.8 with lower bias current in the output stage and does not operate Class A to 60 watts. However, the first 30 watts are pure Class A. Pass Labs states, "The essential details that deliver the sound of the .8 Series have been tweaked in the subjective testing, and the result is very close. Another major change in the INT-60 is that the volume control circuit outputs are buffered by six-dB gain stages, whose input JFETs present many megohms of load, getting attenuator distortions down below the .001 percent line. The extra gain allows optimal figures for the power amp stages and offers improvement over the previous 'passive' circuits."
The INT-60 delivers 60 watts into eight ohms and 120 watts into four ohms. Regardless of what speakers I used or volume levels I attained in my months of auditioning this wonderful integrated amplifier, it never left pure Class A rating except for a few brief seconds on gargantuan crescendos that were well over 100 dB in volume.
As to be expected from Pass Labs, the superlative build quality and visual appearance of the INT-60 compete with any equipment on the market today. The dimensions of the INT-60 are 7.6 inches high by 19 inches wide by 21.2 inches deep, and it weighs 93 pounds. On the beautiful silver front panel, the following are located from left to right: the standby power button; a display that shows volume level; input buttons one through four with input LED indicators; a bias meter; an IR window; volume control; a mute LED indicator; and, lastly, the mute button. On the rear panel, you will find the IEC input, the main power on/off switch, XLR and RCA preamp outputs, XLR and RCA preamp inputs, and two pairs of very high-quality speaker-wire connections.
The remote control is built out of high-grade aluminum, is easy to use, adjusts the volume, and controls the on/off switch, mute, and input selection.
Pass Labs uses some of the finest shipping boxes/materials to ensure that your purchased piece(s) arrive in pristine condition. The INT-60 demo unit sent to me was brand new, so I put at least 100 hours of burn-in on it before I started my serious listening sessions. I inserted the INT-60 in both my large reference system and my smaller auditioning system. Speakers that the INT-60 powered during the review process included Lawrence Audio Cellos and Double Bass, Bache Audio 002AB, Clearwave Resolution BE, Silverline Prelude Plus, and Role Audio Enterprise. My source was the MBL 1621 transport, which drove the Concert Fidelity-040 battery-powered hybrid DAC. All the wiring in both systems was Silver Reference MG Cable IC and MG Cable Reference Three Copper Speaker Wire. Both auditioning systems use a combination of Harmonic Studio Master and Ensemble reference power cords into a Running Springs Audio Dmitri power conditioner.
Click over to Page Two for Performance, The Downside, Comparison & Competition, and Conclusion...