Reviews of Attainable Hi-Fi & Home-Theater Equipment

Reviews of Attainable Hi-Fi & Home-Theater Equipment

201011_icon1Is hi-fi cool? If you’ve ever been to an exhibition of high-end audio gear, you’ve probably noticed that there aren’t many women there, and few members of the iPod generation. The only exceptions are the paid-for eye candy, and kids who’ve usually been dragged there by their fathers.

The lack of women at these shows has never bothered me. Don’t get me wrong -- I’d love it if there were more women. I just don’t know many who are genuinely into hi-fi. I don’t care if hi-fi is a male-dominated hobby. What worries me is the lack of interest by younger music lovers of either gender. More people than ever are listening to music, thanks in part to the iPod, but how do we get them interested in high-fidelity playback?

I have an idea: Buy your son or daughter a budget integrated tube amplifier. I know that may sound a little crazy, but think about it. First, tube amps are very cool to look at: Those glowing tubes can captivate, especially in the dark. Second, they can sound wonderfully musical, and have the power to draw young people deeper into their music. Better yet, many companies now make affordable integrated tube amps. Add a decent DAC and speakers and you’re good to go. I guarantee that your son or daughter will fall in love with the sound, and will have something unique that none of his or her friends have. And the subject of this review, Icon Audio’s Stereo 25 ($800 USD), is a throwback integrated tube amp that brings old-school design into the 21st century at a reasonable price.

Stereo 25

Icon Audio is a small company based in Leicester, England. They make a number of affordable audio components, but are best known for their tubed amplifiers. As they put it, “Our philosophy in this ‘throw away’ world with cheap nasty products is to create amplifiers and speakers that sound good, look good, are easily affordable and will last a lifetime.”

The Stereo 25 is one of Icon’s entry-level models. A basic integrated amplifier of traditional circuit design, it’s said by Icon to have been inspired by the H.J. Leak amps of the 1950s, and indeed, it has a very attractive 1950s look. But what really caught my attention was the 25’s build quality for $800. The fit and finish were first rate, and the first time I lifted the review sample, I could tell that here was no flimsy product. The Stereo 25 weighs a hefty 33 pounds (15kg) and measures 12.6”W x 8.5”H x 12.2”D, and is clearly constructed from quality materials made not only to last but to optimize the sound. On the rear panel are three RCA inputs labeled Tuner, CD, and Aux. The high-quality binding posts have separate taps for 4- and 8-ohm speakers. A tube cage is included.

Modest in power at 30Wpc, the Stereo 25 has a class-A, all-triode front-end using a mixture of 12AX7 and 12AT7 tubes in the preamp section. The amplification section uses the popular EL34 output tubes operating in ultralinear mode. Different tubes are available on request, and the whole unit can be ordered configured to run in full triode mode, in which case it outputs 15Wpc. And you never have to bias the tubes. Adjustment of tube bias is required only if you replace the original tubes with different models. The Stereo 25 has a soft-start function that gradually warms it up, to avoid a tube-damaging rush of current.

Believing that printed circuits boards color the sound, Icon hand-wires every component -- the Stereo 25 contains no PCBs, and Teflon-encased silver audio cable is used throughout. At the base of each tube is a ceramic socket that helps maintain a low level of noise. The polypropylene audio capacitors are audiophile grade, and the transformers are hand-wound using what’s said to be long-grain Japanese steel. Upgrades such as Jensen copper-foil and paper-and-oil capacitors are available for additional cost, and Icon claims to have used minimal feedback in the amp’s design.



The Stereo 25 came fully broken-in, so I let it warm up for a good hour, then jumped right into listening. I tossed on the acoustic version of the Foo Fighters’ “Everlong,” from their Greatest Hits (CD, Sony Music 88697-36921-2), and was presented with a very transparent midrange. Dave Grohl’s voice was tonally full and sounded quite natural, with no spotlighting of any frequency. I wasn’t hearing the typical euphonic tube sound. The Stereo 25 leaned toward the warm side of the tonal spectrum, but was surprisingly closer to neutral than I expected to hear from a tube amp. The Icon had a very warm overall sound that made recordings come to life, especially in the midrange.

In fact, the 25’s sound was decidedly smooth. That warm character carried over to Grohl’s acoustic guitar, which had real presence -- it sounded like an actual guitar would have in my room. I heard a lot of detail; e.g., Grohl sliding his fingers along the strings to change notes, something that lower-quality amps have masked. Like many good tube amps I’ve heard, the Stereo 25 produced sound that seemed completely disconnected from the speakers, to create a very layered soundstage. The imaging was very good, even outstanding, considering the price.

To test the Icon’s bass capabilities, I played “Ramble On,” from Led Zeppelin II (CD, Atlantic 82633-2). The bass was typical of what I expect from tube amps: it did the job, but wasn’t as tight as, and didn’t have the snap or control you get from a good solid-state amp. This somewhat diminished the rhythm and pace of good rock songs such as this. Otherwise, the Stereo 25 fared quite well with this track, with enough sonic energy to grab my attention and draw me in.

I was impressed with the Stereo 25’s apparent power output: It easily drove my PMC fact.8 speakers to high decibel levels. The only time I could tell that I was listening to a low-powered amp was when it tried to reproduce recordings with huge dynamic range -- it just didn’t have the headroom. But if you mate the 25 to a pair of speakers of relatively high sensitivity, I’m sure this won’t be a problem. The fact.8’s claimed sensitivity of 89dB/W/m indicates a speaker slightly more sensitive than the average; that definitely paid dividends with the Stereo 25.

I then listened to the title track of John Coltrane’s Blue Train (CD, Blue Note 95326). It sounded fabulous through the Stereo 25. Coltrane’s tenor sax was lifelike and natural, in the best senses of those words, with an inviting smoothness that drew me into the music. The double-bass was deep and weighty, and I could clearly hear the inner details of the crash cymbal in the background. There was, however, a slight grain to the cymbals, something I’d noticed while listening to the Led Zep cut. When Robert Plant sang words with sibilants, they sounded a touch sharp or hissy. In short, the Stereo 25 had a tendency to sound a little edgy in the highs. It wasn’t horribly noticeable, but I did hear it while listening through a very revealing set of speakers. Nonetheless, the highs had good definition, and I never suffered from listener fatigue.

I compared the Stereo 25 with my own Peachtree Audio Nova integrated amplifier ($1199), a hybrid design that can use either a tubed or a solid-state input stage. Both integrateds had a very open, transparent midrange. Voices sounded natural and lifelike through both, though warmer through the Stereo 25.

Where the two amps most differed was at the opposite ends of the audioband. The Nova clearly had better control of low frequencies, and was capable of more defined bass. The Stereo 25 has less-defined bass overall, but wasn’t bloated or sloppy in any way. The high-frequency response was a closer race, and here the Nova had a slight edge in extension. Both had good definition in the highs; neither was the best I’ve heard, but both are competitive in the realm of budget integrateds. As with most tube amps, the noise floor of the Stereo 25 was more audible, but I noticed it only when I got very close to the speakers.

Overall, these are two very good budget integrated amplifiers. I can imagine each suiting the sonic priorities of different listeners.


The Stereo 25 is a very good budget amp. Yes, there were some tradeoffs in sound, but they weren’t enough to interfere with my listening pleasure -- and that’s what counts. The 25’s beautiful, transparent midrange more than made up for any nits I had to pick. Voices sounded enchanting through this little tube amp. There, the Stereo 25 had that “magic” that connoisseurs of tubed products talk about. At 30Wpc, the Stereo 25 is no powerhouse, but with the right (read: sensitive) speakers, it provided enough power to let me enjoy everything from rock to jazz. Icon Audio has packed into the $800 Stereo 25 enough serious value that the iPod crowd might just stand up and take notice.

. . . Kevin Gallucci

Associated Equipment 

  • Speakers -- PMC Fact.8
  • Source -- Oppo BDP-83 Blu-ray/SACD/DVD-A/DVD-V/CD player
  • Speaker cables -- Monster MCX-2
  • Power conditioning -- Lindy six-outlet power conditioner

Icon Audio Stereo 25 Integrated Amplifier
rice: $800 USD.
Warranty: Two years parts and labor.

Icon Audio
351 Aylestone Road
Leicester, Leicestershire LE2 8TA
England, UK
Phone/Fax: +44 (0)116 2440593