amps

NuForce is a high-end company that makes an unusually wide range of products, from the tiny uDAC-2 portable headphone amp ($129) all the way up to the Reference 18 power amplifiers ($6,600 for a stereo pair). NuForce is based in Milpitas, Calif.

Today we'll be looking at the Icon iDo, a dedicated USB digital-to-analog converter/headphone amplifier designed to work with iPods, iPhones, and iPads, which cannot be used as a USB/DAC with computers. The iDo is awfully little, it's just 6 by 4.5 by 1 inches, and it shares its all-metal chassis with NuForce'… Read more

We test a lot of headphones here at CNET, and the good ones tend to set you back more than $100. But a new headphone company, Sol Republic, is hoping to change that with a line of headphones that deliver very good sound and durability for a more affordable price.

In case you're wondering what "sol" stands for, it has nothing to so with the sun but is an acronym for "soundtrack of life." The company's founders have a good pedigree in the headphone business, and co-founder and CEO Kevin Lee is the son of Monster Cable founder Noel Lee and is credited for driving the popular Beats by Dr. Dre line of headphones at Monster. … Read more

This Top-10 list of great-sounding solid-state and vacuum-tube amplifiers includes headphone amps and vintage models. Most are light on features, so if you need autosetup, GUI menus, AirPlay, iPod/iPhone/iPad compatibility, home networking, HD Radio, Bluetooth, HDMI switching, digital-to-analog converters, Dolby and DTS processors, that's not the main plan. The focus is on amps that provide the maximum sound quality for a minimal investment, but I included one receiver with some of those goodies.

I'll do a top-10 affordable speaker list soon.

Dayton Audio DTA-1 Amplifier ($40)

It weighs almost nothing, looks cheap and flimsy, but Dayton'… Read more

I recently bought a NAD 3020 integrated amplifier on eBay for $66. The little amp was a smash hit in 1980 and instantly put NAD on the map. While the amp made its reputation as a giant killer, it's not very big--just 16 by 3.75 by 10 inches. And the look is bare-bones basic. The sound is something else again; as soon as I fired it up I remembered why budget-minded audiophiles bought more than a half million 3020s in about three years, making it the best-selling integrated amp of all time.

It was rated at just 20 … Read more

The nice folks at Parts Express sent over an amazing-sounding little amplifier, the $129 Topping TP30. It's a tiny desktop Class T amp design, with one analog RCA stereo input and one USB connection (the TP30 has a built-in digital-to-analog converter). The amp delivers 15 watts per channel to 4 ohm-rated speakers (10 watts into 8 ohms), and has a 3.5 mm headphone jack on the front panel.

With its extruded aluminum chassis, 8mm thick, CNC-machined front panel, and solid-metal volume control knob the TP30 wouldn't look out of place in a high-end system. It even feels expensive, but I have just one nitpick: the illuminated blue LED ring surrounding the volume control knob is too bright. I wish there was a way to dim it or turn it off. The amp measures a tidy 4.13 inches by 1.77 inches by 8.07 inches.

The USB interface utilizes standard Windows audio class 1 drivers (it worked fine with my Mac mini). Internal parts quality is superb; the TP30 boasts Elna capacitors, Dale resistors, and an ALPS volume control. The Burr-Brown USB digital-to analog converter chip accepts up to 48 kHz sampling rates with 16-bit resolution.

I compared the sound of the TP30 with my Audioengine N22 amp ($199), and they're both pretty good. The N22 has a fuller, warmer tonal balance, but the TP30 has a more immediate, detailed sound with more tightly controlled bass. I used my Audioengine P4 speakers for all of my speaker-based listening tests. It's interesting, the TP30 is a digital amp and takes digital signals "straight-in" via its USB port; the N22 is analog-only and is a more traditional Class A/B amplifier design. It sounded softer, and a wee bit less defined than the TP30.… Read more

I don't remember who told me about Bottlehead, but I'd like to thank whoever it was that made the introduction. I review and play around with a lot of audio gear, and as much as I love great budget stuff, the best-sounding products are always a lot more expensive. Not this time; the Bottlehead Crack amplifier I'm reporting on today goes for just $219, and it sounds like it's five times that price. Bottlehead has been selling electronic kits for 17 years.

First things first; $219 buys the Crack as a build-it-yourself kit, but Bottlehead's founder Dan Schmalle assures me the kit is super easy to build by anyone who knows which end of a soldering iron gets hot. It should take an evening or two to complete. The Crack is an output transformerless amp, specifically designed for high-impedance (100 ohms or higher) headphones like many Sennheiser, AKG, and Beyerdynamic models (Bottlehead offers other amps tuned for low-impedance Grado, Audio Technica, etc., models).

Most Bottlehead customers buy the kits, but the company sells factory-assembled Crack headphone amps for $369, and considering the Crack's build and sound quality, it's still a major deal. The amp's chassis, real wood base, power transformer, PC boards, and even that nifty little Bottlehead badge are all made in the U.S.A. The Crack is a bit bigger than most desktop amps--it's 7 inches wide and 11.25 inches deep--and it was designed by Paul Birkeland.

I first tried the Crack with my high-impedance Sennheiser HD 580 full-size headphones. I bought these at least 10 years ago, and played 'em with countless receivers and headphone amps, but the Crack took the HD 580's sound to the next level. The sound was pure and clear, but never hard or bright. That's what the best tube amps do, you hear more of what's going on in the music, minus the edge or false hyped "detail" of typical budget-priced headphone amps. The Crack delivers bona fide high-end sound.… Read more

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. … Read more

Gary Ali has hand-built well over 8,000 Portable Pocket Amplifiers since 2004. He now sells the Version 2 model, the PA2V2, for $60, and that price includes shipping charges (he's in Toronto). I chatted with Ali by phone yesterday, and he seemed like a really nice guy.

His site, Electric-Avenues.com, is basic in the extreme, and lacks the usual shopping cart buttons and simplified ordering instructions. It doesn't state the PA2V2's price, so that was the first thing I asked Ali about. He explained that he likes talking to his customers one at a time, … Read more

I've written about better-than-iPod-sounding music players before, but this is my first portable headphone amplifier review. The Todd The Vinyl Junkie Portable Slim amplifier ($349) really works and will take the sound of an iPod, or any portable player, to the next level. The amp's sleek chassis (4.2x2.7x0.4 inches) is nearly the same size as an iPod Classic. It's built in Dallas, and the case comes from Canada.

The Slim's rechargeable lithium ion battery provides 15 hours of playback time. It recharges in about 2 hours from a USB port or a USB … Read more