Schiit Audio's very first product, the Asgard headphone amplifier, left me shaken and stirred back in 2010. It sold for $249, looked and sounded amazing, and to top things off, it was made in the U.S. -- not just assembled here. Most of the Asgard's parts are sourced from U.S. companies.
The Asgard is still in company's product line, and it's still $249. But Schiit has grown since then, and now offers a full line of more expensive headphone amps and USB digital-to-analog converters (DACs) -- which is great. But the company's most recent offerings sell for just $99 each! The Magni headphone amp and the Modi DAC are also made in America, and they sound spectacular.
They're both the same ultra-compact size, just 5x3.5x1.25 inches, and they each weigh about a pound. Both feature an all-metal case, and the design looks pretty serious. The Magni amp puts out up to 1.2 watts, so it's considerably more powerful than your average AV receiver's headphone amp. And unlike those built-in headphone amps, the Magni is not a chip-based amp that costs 20 cents. Most headphones don't need all that power -- but some headphones, like my Hifiman HE-400s, really come alive with more potent amps.
Yes, what you plug your headphones into can make or break their sound. Heck, most $1,000 receivers have marginal headphone amps. (They're not a big priority for most buyers.) But the Magni's innards feature fully discrete FET/bipolar, Class AB circuitry. That means the Magni is built like a miniature high-end speaker amplifier. I don't know of another headphone amp built that way for less than $250, and most $250-$500 amps aren't built as well as the Magni. The amp has just one set of RCA analog inputs on its backside, and a 6.3mm headphone jack on the front panel.
The Magni amp uses an external wall wart power supply; the Modi DAC is powered via the USB 2.0 asynchronous input connection. The USB is the only digital input -- there's no coaxial or Toslink optical inputs, but there's a pair of RCA analog outputs on the rear panel. The DAC handles up to 96kHz/24-bit digital audio. The Modi features switched-capacitor filtering and an active filter section, so you can run long analog cables from the Modi back to your hi-fi system without any loss of quality.
I played the Magni and Modi together, and loved the sound. Like the bigger Schiit amps I've tested, the sound is rich, with lots of detail and oomph. I started with my old Sennheiser HD 580 and Grado RS-1 headphones, and moved onto the brand-new Yamaha PRO 500, Sony MDR-1R, Noontec Zoro, and Koss Porta Pro over-the-ear and on-ear headphones, plus a few in-ear models, including Ultimate Ears UE 900s. I have quite a few more expensive desktop amps on hand, including the other Schiits at my disposal. But there was nothing about the sound of the Magni/Modi combo that I found wanting. They deliver bona-fide high-end sound quality. A lot of desktop headphone amps aren't quiet enough to use with in-ear headphones, but the Magni is.
Then I compared the Modi with the $449 Schiit Bifrost DAC, and it was easy to hear the difference. The Modi is sweet and mellow and very tolerant of cruddy-sounding low bit-rate files and streaming audio sources. But when I played great-sounding CDs, the Bifrost was a lot more transparent and detailed. There's less standing between my ears and the music. But as I did the Modi vs. Bifrost shootout, my respect for the Magni amp's sound went up. The $99 amp easily resolved the differences between the two DACs over my Hifiman HE 400 headphones. Stepping up from the Magni to the Asgard produced similar improvement, but to a much smaller degree. The Magni would still be an outstanding value for double the price.
The Magni and Modi come with two-year warranties. That's twice the coverage of most desktop components in their price range. Schiit has a 15-day return policy, so you can still send it back for a refund if you're not happy with the sound, but there is a 15 percent restocking fee.