Pass Labs INT-250 Integrated Amplifier

The Outer Limits

Equipment report
Integrated amplifiers
Pass Laboratories INT-250
Pass Labs INT-250 Integrated Amplifier

Since I had still had the superb Esoteric K-03X disc player in-house (reviewed in Issue 261), I was primed to return to a favorite recording that I referenced in the INT-150 review. It was the SACD of Anna Netrebko singing Donizetti’s “Ardon gli incensi” on the DG SACD Sempre Libera. She’s accompanied by a playful glass harmonica that urges her voice upward past a high C, while the delicate layering from the Mahler Chamber Orchestra and chorus defines the limits of the hall behind them. I know I’m quoting myself but, as I said then, for those audiophiles who maintain LP and SACD collections this is where the Pass Labs will show you the money. Its micro-dynamics, fluidity, and spatiality plays to the strengths of these enriched formats and can leave you breathless.

Since the INT-250 was designed for the grunt work of driving low-sensitivity loudspeakers, roughly 86dB and below, my first thought was, “Have I got the loudspeaker for you.” My own ATC SCM20-2SL compacts are the passive version of the company’s active pro monitor. Rated at 83dB sensitivity—a Marat/Sade-like spec—I figured the ATC’s would give the INT-250 a sufficient run for the money. Interestingly the pro version of the ATC is driven in a biamplified configuration allotting 200W to the woofer and 50W to the tweeter—250 watts total, just like the Pass Labs. I know this loudspeaker like the back of my hand. I own it and it has labored steadily as my reference compact for years. It’s an acoustic-suspension thoroughbred, tonally neutral and balanced, capable of superb resolution, pitch control, and transparency, with solid midbass response into the 40–50Hz region (and perceptibly lower depending on the room reinforcement). However, it’s also a real trouble-maker. It can sound shockingly dull and dynamically flat when driven by lesser, power-challenged amplification. It thrives on a level of juice that doubles down at 4 ohms, and yes, is also a stickler over the quality of that power.

The INT-250 set a new benchmark for the ATCs. Like a sports car suddenly given another gear, the ATC found a new level of speed and resolution. The airspace between orchestral images was more defined. Textural details were more clarified. Often, low-level information—the harmonic decay of a piano and resonances of cello or of drum skins, for examples—extended a little further.

A true reference integrated such as the 180Wpc MBL C51 made it a contest throughout most of the audio spectrum, but the difference in the Pass Labs’ raw power was telling in midrange dynamics and mid/upper-bass grip. In my experience only the Vitus Audio SIA-25 (Issue 218), a pure 25Wpc Class A integrated, has exhibited a more transparent top-end but its relatively low power removes it from the equation with lower-sensitivity loudspeakers.

Finally I should add that the INT-250’s soothing and seductive sonics proved an ideal companion for analog LP playback. It just makes you want to spin vinyl, to take a moment to slow life down a bit and appreciate the gatefold art or follow along with the lyrics, or check out who’s playing drums, or singing backup on a particular track—elements that are all missing when I plug in a USB stick. With something like Mobile Fidelity’s newly remastered, two-disc, 45rpm mono pressing of Jefferson Airplane’s Surrealistic Pillow, it’s hard to imagine ever sitting down to listen to Grace Slick’s fluttering vibrato on “White Rabbit” and “Somebody to Love” on any other format again.

The INT-250 is a force to reckon with. With musicality that is second to none, it operates at the outer limits of what is currently possible in today’s integrated amplifier marketplace. It does have rivals breathing down its neck, and it’s heavy lifting both physically and financially, but overall I simply don’t know of a better integrated amplifier in the world today. 


Power output: 250Wpc into 8 ohms, 500Wpc into 4 ohms
Inputs: Four RCA, two XLR
Outputs: Two RCA and XLR
Dimensions: 19" x 21.5" x 9.06"
Weight: 105 lbs.
Price: $12,000


13395 New Airport Road, Suite G
Auburn, CA 95602
(530) 878-5350