Reviews of Attainable Hi-Fi & Home-Theater Equipment

Reviews of Attainable Hi-Fi & Home-Theater Equipment

Note: for the full suite of measurements from the SoundStage! Audio-Electronics Lab, click this link.

As I’ve said any number of times, you’ll never find a completely unbiased audio reviewer. We’re human. We have our preferences. We like what we like. As such, it’s a personal policy of mine to bold, italicize, and underline any inherent bias when I sit down to write a product review. And that’s the only way I can think of to introduce a review of any piece of Arcam gear. The name “Arcam” alone gets me a bit excited, mostly because of my experiences with the company’s higher-end A/V receivers, but that excitement also spills over into two-channel products, such as the new Radia-series A25 integrated amplifier ($1499, all prices USD).


I must admit, though, things have changed since the last time I tested an Arcam component. This is my first review since the company was acquired by Harman and hence Samsung. It’s also my first review of anything from the new Radia family, of course, a line defined by its slimline chassis, slick yellow halo accents, hooded I/O panel, and clean industrial design.

As the flagship integrated amplifier in the Radia line, the A25 also benefits from an amplifier topology most commonly associated with Arcam: class G. If you’re not familiar with class G, it’s functionally very similar to class AB, except that it relies on at least two voltage rails from the power supply—one with higher voltage. The long and short of it is that it’s a linear topology that ameliorates many of the problems with efficiency inherent to class-AB designs, and although it’s not quite as efficient as class D, it avoids some of its potential technical shortcomings, as well.

In most cases, in most systems, with most loads, in most listening conditions, it’s highly unlikely you’d ever hear the differences. In fact, you almost certainly wouldn’t. But what I love about class G is that it’s a much more efficient topology that might appeal to audiophiles who have an inherent bias against switching amps, and anything we can do to decrease energy usage without impacting fidelity is a very good thing in my book.


Specified output for the A25 is 100Wpc into 8 ohms (full range, both channels driven) or 165Wpc into 4 ohms (1kHz, both channels driven). All told, it features three line-level inputs and a moving-magnet phono input (all stereo RCA), two coaxial digital inputs and one optical, and—curiosity of curiosities—a USB-C DAC input in lieu of the standard Type-B connection. The USB-C port also supports DSD. You also get a stereo preamp out (RCA), a handful of control connections (3.5mm IR in, trigger in, and trigger out, as well as a proprietary control connection for use with other Radia gear), a USB-A port for firmware updates, and some nice five-way binding posts for speaker-level connections. There’s also a junior-sized 3.5mm headphone jack on the front panel.

As mentioned above, the I/O section is hooded, so it might be tough to reach all of the guzintas and guzouttas if you’re typically the type to lean over the top to make connections. But I dig the aesthetic once everything is connected.


In terms of wireless connectivity, the A25 doesn’t have any provisions for home networks—that sort of thing is relegated to the ST5 streamer. But it does have Bluetooth connectivity, with a version 5.2 chip that supports aptX Adaptive.

Setting up the Arcam A25

One thing that Arcam seems almost reluctant to advertise is that the BT connection also supports the AAC codec, which is a nice bonus for us Apple stans. I found this out as I was pairing my iPhone 12 Pro Max with the A25, the connection with which I wanted to test briefly before moving on to other matters. As soon as I pressed play, the front-panel display responded accordingly, flashing a message of “Bluetooth AAC,” along with a volume level of 30.

A quick listen revealed the volume to be entirely too low to be really satisfying, but a quick dig through the menus showed that, in addition to things like a headphone override, which allows you to keep your main speakers playing when you plug in a pair of cans if you wish for whatever reason, the A25 has a separate audio settings menu—with separate volume limits—for the Bluetooth connection. By default, the max for BT was set to 30 when my review unit arrived, but it was easy enough to adjust that to 40.


This may be handy if you have kids in the house and Elroy and Judy are more likely to connect to the hi-fi via Bluetooth while Jane and George rock out to a legacy source device. Or your reasons for wanting the max volume for BT and other sources to be the same or different may be entirely your own. At any rate, it’s nice that the capability is there. And as of firmware v1.34, which was released as I was working on my review, that default volume cap for BT has been raised to 40, but that’s as far as it would let me go.

One other thing worth shining a light on is that the A25 has selectable reconstruction filters for its DAC, tucked away in a wholly separate setup menu accessible via the button on the remote denoted by a musical note. The manual incorrectly states that, for the A25 in particular, the default filter is the Linear Phase Fast option. This wasn’t the case upon bootup for me. Instead, the Hybrid Fast was selected by default. I switched this over to Linear Phase Fast, bypassing the Minimum Phase Slow filter, which was frankly the only one of the three that sounded meaningfully different when I tested out all three using CD-quality streams. With high-res, they all sounded so close that I couldn’t identify which was which with my ears alone.


By the way, one consequence of the lack of network connectivity is that firmware updates have to be done via USB, but the process was quick and easy. Whilst on the product page, though, I noticed something missing that I would normally expect to see for Arcam products: drivers for advanced control systems such as Control4, Crestron, etc. The lack thereof probably isn’t too relevant to SoundStage! readers, but it’s worth pointing out.

Other than that, there’s not a lot to talk about with regard to setup. I connected my Maingear Vybe media and gaming PC to the USB-C input of the A25, ran an optical cable from my Oppo BDP-93 disc player, and added Arcam’s aforementioned ST5 streamer to the AN 1 input. As usual, my Paradigm Studio 100 v.5 towers were connected via a pair of Elac Sensible speaker cables.


Unlike Arcam’s older (and much pricier) SA30 integrated amplifier (originally $3300, now $1980 most places until stock runs dry, one assumes), the A25 doesn’t feature Dirac Live room correction. There’s also no dedicated subwoofer output and no bass management (although you could easily connect a sub to the pre-out), so I didn’t test it with a sub. So there really wasn’t much else to do other than sit down for some critical listening.

How does the A25 integrated amplifier perform?

I started my critical listening by switching to the USB-C input and loading up “Loyalty” from King Gizzard & the Lizard Wizard’s Polygondwanaland (24-bit/44.1kHz FLAC, ATO Records / Qobuz), a song I rarely pick from my power-supply-stress-test playlist, simply because when I want to listen to anything from Polygondwanaland, I want to hear the whole damned album. But the rest of the tunes in that playlist are starting to get overplayed in reviews, so I chose to suffer for my art.

What makes “Loyalty” such a great track is that, starting at around the 0:42 mark, there are some delicious bass drops that set the tone for the song. With something like Emotiva’s excellent BasX TA1—a banger of a stereo receiver for those with 2.1-channel speaker setups—I never could get as much force as I wanted from the bottom end through my Paradigm towers, and I felt a general thinning out of the less-dominant bass that kicks in at around 0:58.


From there until around 1:25, the bottom end of the mix is precisely enough. It’s exactly in balance. But that means if any of it starts to recede as a result of an amp struggling to power through the impedance dips of my Paradigms, as it did with the TA1, the song can sound a little thin.

Through the A25, the mix simply couldn’t have been better balanced, which indicates to me that the power supply here is up to snuff and the damping factor is sufficiently high.

Switching over to something a little more audiophile-friendly, I pressed play on “24.03” from Hania Rani’s Ghosts (24/48 FLAC, Gondwana Records / Qobuz), a keyboard-heavy piece that features some of the most adventurous mixing of any of her music to date. What I love about this one is that Rani plays with space the way Jackson Pollock played with hue and value, and as such—despite the very Ned Lagin-esque electronic-ness of the soundscape—imaging and soundstaging are delicate here, teetering right on the edge of falling apart. The oscillations and convolutions whoosh and dart and swing through the air with pinpoint precision, and should anything come up lacking in terms of soundstage depth or width, it just wouldn’t work.


Through the A25, it did. Brilliantly. “24.03” also proved to be one of a tiny handful of tunes in which I could hear a truly meaningful difference between the Bluetooth reception of the A25 and the AirPlay connection of the Radia ST5 streamer. And it wasn’t really in the keyboards themselves where I heard the biggest difference, but rather in an element of the mix that sounds like hysteresis. Whether it’s a consequence of the console, the room in which the music was recorded, or the effects pedals through which she’s playing, I don’t know. But it’s there, and the character of it got ever-so-slightly hashy on the Bluetooth, but not AirPlay. Not to a distracting degree, mind you, but if you’re in hardcore critical listening mode, it’s the sort of thing you might notice.

I also found that the volume limit on the Bluetooth connection was too low with this one, given how dynamic the mix is. Via the ST5, I found the most comfortable listening level for this track was right around 44 or 45, and no setting would allow me to get the BT input of the A25 to go higher than 40. Maybe Arcam will fix this in a future firmware update.


Either way, what I found really lovely about the A25’s rendering of the song was the way it conveyed the deep, at times almost subsonic, bass that should be—and was—felt more than heard. It’s a difficult mix to get right on any system, given that everything has to go right in terms of tonal balance, channel balance, and transient response, and you can’t have anything stupid going on with the DAC’s reconstruction filters. But I thought the Arcam nailed it. Hard.

Speaking of hard, I wanted to see how much the A25 would heat up when pushed to its limits. As mentioned above, class G is a much more efficient topology than class AB, but the A25’s output is biased quite high—unless I’m remembering wrong, it operates in class-A mode up to 15W—and this thing’s chassis is packed tight as heck. So I did worry a little about heat.


Loading up “Spoonman” from Soundgarden’s Superunknown: 20th Anniversary (24/192 FLAC, A&M Records / Qobuz), I cranked the volume to 47, which was as high as I could tolerate it, put the song on a loop, and left the room. When I came back 15 minutes later, the chassis was comfortably warm, but nowhere near hot. So that’s good. Very good.

What other integrated amps in this price class should you consider?

To the surprise of exactly no one, I have to say that if you’re shopping for an integrated amp in this price range, you should also seriously consider the NAD C 3050. It sells for $100 less at $1399 without the BluOS-D module, which adds Dirac and BluOS streaming, not to mention advanced bass management.

The C 3050 sports a very different aesthetic that may or may not appeal to you. It also only has one line-level input. But it also has a phono stage with support for MM cartridges, and it adds an HDMI ARC connection; B speaker connections; and a proper, adult-size headphone jack. It’s also more upgradable owing to the MDC2 Modular Design Construction slot on the back.

TL;DR: Should you buy the Arcam A25 integrated amplifier?

If you’re installing an integrated amplifier on a table or countertop in your family room or office or what have you, and you’re struggling to find something that looks nice when not in a rack, the design of the A25 is something to behold. It’s a gorgeous piece of kit, which is hard for me to admit given that it totally eschews the sort of vintage vibe I prefer. How on earth an amp manages to look this good without VU meters is a mystery.


It also sounds really lovely—punchy, dynamic, detailed, refined, with great imaging and soundstaging, and oodles of current on reserve by all indications. My only real nits to pick are the excessive volume limiting on the Bluetooth input and the fact that I feel like they artificially withheld network connectivity from the A25 to justify the existence of the ST5 streamer.

If you don’t need the network connectivity—say you’ve got all the sources you need and you’re perfectly happy with slightly quieter Bluetooth for your wireless connection needs—there’s so much to love here. If this is an indication of where Arcam is headed, I’m legitimately excited, if only because it means more people will be exposed to this beloved brand.

. . . Dennis Burger

Note: for the full suite of measurements from the SoundStage! Audio-Electronics Lab, click this link.

Associated Equipment

  • Speakers: Paradigm Studio 100 v.5.
  • Speaker cables: ELAC Sensible.
  • Interconnects: Straight Wire Encore II.
  • Sources: Maingear Vybe PC; iPhone 12 Pro Max; Oppo BDP-93 Universal Network 3D Blu-ray disc player.
  • Power protection: SurgeX XR115 surge eliminator / power conditioner.

Arcam Radia A25 Integrated Amplifier–DAC
Price: $1499.
Warranty: Five years, parts and labor.

The West Wing
Stirling House
Cambridge CB25 9PB
Phone: 1-888-691-4171