Parasound JCA100 Tribute monoblock power amplifier

In December 2023, I took the train from New York to Los Angeles to attend the Los Angeles & Orange County Audiophile Society's 30th annual Gala. I took the trip because it is both stimulating and satisfying to spend an afternoon in the company of more than 200 audiophiles and music lovers; I also wanted to see John Curl presented with the Society's fourth Innovation Award, by George and Carolyn Counnas of Zesto. John was given the award "for his groundbreaking contributions to the field of solid-state audio amplifiers, circuit innovation, mastering recorders and much more."

I first met John more than 40 years ago, at a Consumer Electronics Show in Chicago, where I was blown away by John's intuitive and innovative approach to circuit design. As J. Gordon Holt wrote in his 1988 review of John's Vendetta phono preamplifier, "In the pursuit of audio perfection, Curl little comprehends the meaning of 'compromise.' His designs tend to be truly no-holds-barred, using the best components money can buy to produce the best sound and highest reliability the state of the art allows."

Along with Nelson Pass, Keith Johnson, Dan D'Agostino, and Bob Cordell, all of whom are still with us, and Charley Hansen, Bascom King, and James Bongiorno, who have passed on, John is up there in the pantheon of American designers of solid state amplification products.

After working on video recorder design at Ampex, John Curl designed and built the sound systems for The Grateful Dead's road shows, then designed the legendary Mark Levinson JC-2 preamplifier and the electronics for David Wilson's UltraMaster tape recorder. John Curl met Parasound founder Richard Schram in 1989, and since then Curl has designed all of the Bay Area company's high-power amplifiers as well as consulting on the design of the low-level circuits of many of the company's other components (footnote 1). I enjoyed a beer with John in the Buena Park Hilton's bar after the Gala. I also chatted with Parasound's new owner, David Sheriff, who had acquired the company in December 2022 following Richard Schram's retirement.

The first new product from Parasound under Sheriff's ownership is the subject of this review, the JCA100 Tribute monoblock power amplifier, which is priced at $30,000/pair. The JC in the amplifier's name stands for John Curl; A100 refers to the fact that the output stage is biased into class-A up to the maximum power of 100W into 8 ohms. "Tribute" is indeed intended as a tribute to John Curl's lifetime of achievement.

Only 100 pairs of JCA100 Tributes will be made, each set hand-assembled to order in the United States, Sheriff told me, with a lead time of 4–6 weeks from the placement of the order. Notably, a significant portion of the proceeds goes to Curl. "We are using this as an avenue to 'give back' financially to John in a meaningful way," Sheriff wrote in a follow-up email, adding that Parasound "will also be using substantial portions for scholarship seedings for future repair techs (a dying breed right now, but still much needed)."

The JCA100 Tribute
When I unpacked the amplifiers, I was somewhat surprised that, other than the "97L" and "97R" serial numbers on their front panels (footnote 2), they didn't look any different from the Parasound Halo JC 1+ monoblock that I reviewed in Stereophile's June 2020 issue. (A full description of the JC 1+'s design, components, and construction can be found in that review.) The JCA100 has an identical chassis with substantial heatsinks on the sides, the same controls and connections; it even has a "JC 1+" legend on the rear panel. I asked Sheriff if the new amplifier was based on the older amplifier.

"Correct," he responded. "We intentionally wanted people to understand that this is a limited-run, modified JC1+ tribute edition. Quite a bit of engineering and testing. We will not be offering conversions/upgrades from JC 1+ to JCA100 or JCA100 specifications."

I asked if I would be correct in writing that to manufacture a JCA100, Parasound takes a JC 1+ from its US inventory, modifies it, and replaces the front panel with the new one that has the limited-edition serial number.

"Two JC 1s get modified into the matching set, blueprinted for performance, faceplate/ears/feet swapped." Sheriff said that there will be other tribute products over the next couple of years—a preamp and a phono preamp—which can be supplied to match. "The PRE and PHONO will only be available with the serial number to the purchaser with the same serial on the JCA100s," he wrote.

The new amplifier's specifications indicate that the output stage's bias current has been increased so that the amplifier runs in class- A up to the specified power of 100W into 8 ohms. This power is much lower than the JC 1+'s maximum of 450W into that load. I asked what design decision underlay this reduction in maximum power? Were there other modifications and changes to the circuit?

Darren Myers, Parasound's new Vice President of Research and Development, explained that "the goal of this design was to create an amplifier capable of 100W of class-A operation into 8 ohms. To accomplish this, the voltage rails on the output stage were lowered, reducing the maximum voltage swing into 8 ohms compared to a stock JC 1+. This allows for a manageable amount of power dissipation on the output stage while having adequate quiescent current to achieve the 100W class-A power specification.

"To optimize this class-A operation, there are several internal modifications applied to the circuit, including transformer and component value changes. John Curl worked directly with the Parasound design team for over a year to design and optimize the modification process. John and the entire team at Parasound are so proud of what we've come up with. The outcome is truly something very special."

Footnote 1: An interview with John Curl can be downloaded from

Footnote 2: Sheriff chose the review samples' serial numbers to reflect the fact that Stereophile's website first saw the light of day in 1997.

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CG's picture

I have to applaud Parasound here.

Unlike an awful lot of other manufacturers, based on the power consumption they specify this amp really appears to run fully Class A up to the 100 watts into 8 ohms as they claim.

I have no idea how these amplifiers sound, nor am I likely to ever find out, but it's refreshing to see a company perform like this.

That they are also rewarding John Curl is wonderful, too. It wasn't mentioned in the review, but it's easy enough to read on the internet how he's been taken advantage of by some sleazy companies over his career. About time he gets some reward.

georgehifi's picture

All comes down what Class-B wattage they have, for the same amount of Class-A bias the heat will be exponentially higher for the one that has more B wattage (higher rail volts)
To get "more Class-A" but with the same heat sink area, the class-B wattage (rail volage) has to be much lower.
But this baby still has enough for most speakers and will sound much nicer than the JC1 (even in high bias mode) into those types of speakers.
The only type of speaker I can see being handled better with the JC1 is ones like the Wilson Alexia.

Cheers George

monkeybouie's picture

When you have an amp that’s this expensive, heavy, mediocre and inefficient, what really is the draw here?

It’s not a bad amplifier at all, but it certainly is not state of the art. There are a number of amplifiers that are a small fraction of the price and weight that offer much better performance as well as more power and efficiency.

I’d love to see JA put the Topping LA90 Discrete amp through its paces.

MatthewT's picture

You miss out on a whole world of great gear.

monkeybouie's picture

I guess John Atkinson is a measurement fetishist as well. I mean, come on, he has to be. Seems I’m in very good company.

If there is anyone to be pitied, I’d say it’s you.

MatthewT's picture

Sorry, I just assumed you are an ASR measurement droid. My apologies if you are not.

georgehifi's picture

ASR has it's place, would be nice to see Stereophile going that far with the same amount of measurements (space is a limiting factor as the subjective review takes 2 pages), Amirm that does the measurements for ASR is strictly objective with them, hardly ever commenting on the subjective quality of the sound.

I have noticed those that continually "bag out measurements" don't usually understand/decipher what they're looking at, and are the in the same camp as those that are willing to pay >$400 for a mains fuse and also say they are directional "what a laugh", that are really good quality (Bussmman/Little Fuse etc) re-badged industry standard 50c AC mains fuses.

Cheers George

supamark's picture

No. JA does excellent and relevant measurements, and fully understands what he's doing *and* what the measurements are saying.

Amir does not. Also, s/n beyond like 100 dB or so is pointless - there exists no acoustic recording ever with even a 90 dB s/n because no microphone used to record music gets above about 80 to 85 dB s/n. Not even my stereo pair of Schoeps Colette series omni's (and they're f'ing great mic's, very common in classical recording). The ASR ecosystem's obsession with SINAD is very misplaced and I cannot take them seriously.

Glotz's picture

They do measurement printouts and that's it.

Oh, they ruminate about it afterwards and ban outsiders that don't bow down to their brand of disinformed evil.

(I am still a member because I need to watch the beast grow until it's gestation... and then alert the Vatican. Lmao.)