The world's best headphone amplifier?

I've reviewed and auditioned a lot of headphone amplifiers over the years, but Red Wine Audio's Isabellina HPA LFP-V Edition stood out from the pack. The amp improved the sound of almost every headphone I used with it.

Priced at $2,500 the Isabellina is very much a high-end audio product. Designed and built in Vinnie Rossi's small factory in Durham, Conn., the headphone amp's elegant functionality belies its technical sophistication. Rossi started Red Wine Audio in 2005, and before that he worked on high-speed laser transmitters for Bell Labs.

The Isabellina is more than just a headphone amp; it features a spectacularly good digital-to-analog converter and a hybrid transistor/vacuum tube audio section. While the Isabellina can be run off an AC power outlet, it sounds best powered by high-current lithium iron phosphate (LFP) batteries. Rossi claims "The batteries use organic, phosphate-based material, providing an ideal combination of performance, safety, reliability and environmental friendliness...in fact, more so than any other rechargeable battery technology."

The amp's digital connectivity options include USB, Coax, and Toslink/optical inputs; there are no analog inputs. The Isabellina has analog outputs, so it can be used as a stereo preamplifier, with a separate power amp to drive speakers, or a digital-to-analog converter in a hi-fi system.

The Isabellina features old tech 16-bit, non-oversampling digital-to-analog converters. Rossi acknowledges the latest chips' specifications look more impressive on paper, but he thinks most of them (even some really expensive ones) sound "quite sterile and artificial" in comparison. The Isabellina will work with digital sample rates up to 192kHz, but it will only playback with 16-bit resolution.

The circuit boards are hand-assembled; the chassis is the only part not built in the Red Wine factory. A New Jersey company supplies the metalwork for Red Wine. The amp is pretty small, just 12 inches by 9 inches by 3.5 inches.

I was unaware of the Isabellina's technology when I first heard it at a hi-fi show, but I instantly knew it had a unique sound. That is, it lacks the "edge" that most hi-fis add to the sound of reproduced music. The Isabellina doesn't have that coloration. It sounds remarkably pure, detailed, and clean, but without any false clarity.

Listening at home with my Grado RS-1, Sennheiser HD 580, Audeze LCD-2, Hifiman HE 5 and HE 6P headphones, the amp proved its remarkable sound again and again. That is, acoustic music sounded a giant step closer to the way it does in real life, compared with other headphone amps.

A face-off with the Isabellina and my solid-state Burson Audio HA-160 headphone amp with LCD 2 headphones revealed major differences. The Isabellina was much warmer, fuller, and sweeter. The Burson's brighter, more forward presentation emphasized detail. I preferred the Isabellina on every count but one: dynamics. The Burson rocked harder and was more visceral and powerful sounding. But the Isabellina sounded more like live music.

Listening to Vladimir Horowitz' solo piano recordings I could sense his exact touch, every nuance of his performance was clearly rendered. The Burson smoothed over those differences, so Horowitz sounded more mechanical. Rossi's tube/solid-state amplifier and battery power technology produce superlative sound quality. Listening to lossless iTunes over the USB input was even more amazing. They've never sounded that good before.

In my home theater, the Isabellina/LCD-2 combination sounded as close to 3D/surround as I've heard, without employing special processing. That is, with some movies, like "King Kong," the sounds of jungle birds and giant insects appeared to come from far outside the LCD-2's earcups.

In North America and countries not represented by its distributors, Red Wine Audio products are sold factory-direct, with a 30-day money-back guarantee. The company also offers a stereo preamp, power amps, and other components. All are battery powered. As Rossi improves his designs he offers performance enhancing modifications for older Red Wine products and 100 percent trade-in credit for Red Wine Audio owners when they upgrade to newer, more expensive products. The traded-in products are reconditioned and sold with a full five-year warranty.