Mystère ia21 integrated amplifier

My first trip to a Consumer Electronics Show, in January 2010, was an eye-opener. Not only had I never before seen the phony glories of Las Vegas, it was the first time I'd been to a high-end audio show. Between the offerings on the top floors of the Venetian and T.H.E. Show at the Flamingo, I met some great people and heard some wonderful new products. One of those people was distributor Kevin Deal, and one of those new products was from Mystère. Though I was familiar with the PrimaLuna line that Deal also distributes, Mystère was, well, a mystery. However, after a listen to the Mystère pa21 power amplifier making a pair of MartinLogan speakers sing, and after noting the reasonable prices for some of Mystère's beautifully designed and built amps, I put Mystère in my review queue.

Mystère is a brand of Durob Audio, a Dutch company known for its PrimaLuna and Ah! Tjoeb brands and the Kiseki phono cartridges. Kevin Deal, of Mystère USA told me, "Durob is one of the largest distributors of the most respected brands of audio throughout Belgium and the Netherlands." While all of Durob's products are designed in Europe, they are, like much audio gear these days, made in China.

The obvious comparison for the Mystère line is PrimaLuna. Some folks assume that Mystère is simply an upper-crust version of the PrimaLuna line, as Lexus is to Toyota. Not so. First, the most significant difference between the two lines is that Mystère runs its output tubes in pentode, PrimaLuna in the more conventional triode/ultralinear mode. "I, for one, have a real affection for pentode amps," said Deal. "You let them run without a lot of negative feedback, so the output impedance is slightly higher. You get the color and glory of [a single-ended triode tube], but with power, and the resulting sound is very tasty. When I think about some of my favorite amps over the years, many of them were pentode designs, or a variation on that. Everybody loved the midrange color and richness. Then most amps went to an ultralinear [topology], and some brands used more feedback to get a lower output impedance. Better measurements, but everyone said, 'Something is missing.' I agree."

There are also big differences in the looks of the Mystère and PrimaLuna products. Not only are the Mystère models clad in a gorgeous gloss-black finish (which I usually don't dig, but this one is amazing), they're completely void of bells and whistles. While you can get a remote control, tape outputs, and other conveniences with a PrimaLuna integrated, the Mystère ia21 integrated amplifier ($2995) is a more minimalist product. On the rear it has four RCA inputs, and 4 and 8 ohm taps, and on the front are a selector knob, and, to control the volume, a stepped attenuator built by Mystère. On the side is a rocker switch to auto-bias its KT88 or EL34 tubes. That's it. If you want to hook up a subwoofer, you need to go through the amp's speaker outputs. You'll also need to get your lazy fanny off the couch to change the volume and input. Though Mystère boasts a mysterious-looking Stonehenge logo on its front plate, the ia21 is actually a simple and straightforward amp.

The ia21 is Mystère's most powerful integrated amplifier. Running KT88 tubes, it's claimed to put out 50Wpc of pentode power. The ia21's Adaptive Auto-Biasing makes keeping the output tubes perfectly biased a snap. In my experience, an amp that mismatches the bias between tubes by even 1–2mV doesn't sound as good as one that's been properly biased. The auto-biasing will ensure that your tubes are always in the zone, and eliminate any neuroses you might otherwise develop by worrying if your tube biases are matched. The auto-bias also makes tube rolling fun and easy. In addition to KT88s and EL34s, the ia21 will work with KT66s, 6L6GCs, KT77s, 6550s, and the new (to me) KT120s. Auto-biasing will let the hobbyist in you have a blast while keeping you from constantly having to tinker with your amp. The best of both worlds, I'd say.

"I am your father's brother's nephew's cousin's former roommate."
Setting up the Mystère ia21 was very easy, especially for a tube amp. Take it out of the box, plug it in, select the correct bias setting for the tubes being used, hook up a source and speakers, and turn it on.

The ia21 comes with a tube cage. Actually, cage is the wrong word—it's more like a tube helmet, with two long, skinny slits that provide the only venting for the heat produced by the tubes. The cage's possible inability to dissipate heat worried me, so I didn't use it. Nor did I like the way it looked. With the cage in place, it seemed as if the decapitated head of the Black Knight from Monty Python and the Holy Grail, or Rick Moranis's Dark Helmet character in Mel Brooks's Spaceballs, were sitting there on my audio rack. However, with its cage off, the ia21 was one classy, sexy beast. I found its qualities of fit, finish, and build to be beyond reproach. Though I'm not big into piano-black gloss finishes for my audio gear, I just loved the look of the ia21. That black gloss was inviting yet scary—I knew that if I touched this thing with my bare hands, I'd never get the smudges off. I was afraid that, after one touch, this pretty ia21 would look as if a snotnosed two-year-old had gotten to play audio for the day. So while I find the entire idea of wearing white gloves to touch audio gear a sign of audio fetishism, I did use the provided white gloves whenever I had to touch the ia21.

Mystère–Durob Audio BV
US: Mystère USA
1042 N. Mountain Avenue
PMB 406, Upland, CA 91786
(909) 931-0219

Rowan's picture

Just thought i'd let you know that i've had an ia21 for around a year and a half now.

It really is a solid little performer. I however am running into 98 db efficient speakers so am having absolutely none of the power issues you've mentioned.

I totally agree with you on the EL34's but i find that there is no substitue for the KT88's if electronic music is being played.

The EL34's tend to let the bass fall apart at higher levels. That and the upper mids tend to honk (painfully) when the power comes up.

I highly recomend upgrading the tubes.

I am running Shuguang Treasure Series CV181Z's as replacement to the stock 6SN7's Treasure series 6CA7's as replacement for the EL34's and treasures again for th KT88's

The tube upgrade really does turn this amp into something special

Stage depth and image quality are now almost twice as good!!! I'd call that a grand very well spent

Anyway, that's just some of my opions on it. Thanks for the great review