The Dali Callisto 6 Cs: combining premium sound with wireless convenience
Owning a premium hi-fi has always carried with it a certain amount of compromise. You get great sound, but you also have to put up with a multitude of electronic boxes and the spaghetti of cabling it takes to get them working.
Dali’s Callisto range of premium wireless speakers is intended to get around such issues. There are two options in the range – the smaller stand mount Callisto 2 Cs lose out on a dedicated bass driver and a chunk of cabinet volume to the 6 C floorstanders. If you have a larger room, or crave a presentation full of authority and scale, the 6 Cs are the way to go.
Dali has gone for an engineered look, which doesn’t quite exude the luxurious aura expected of speakers at this level. But the 6 Cs are much more than just speakers. Each of those metre-tall cabinets houses a pair of Class D power amplifiers, a clever hybrid active/passive crossover coupled to 24-bit DSP and all the bits required to make wireless work.
Dali describes these active floorstanders as having a 2.5-way, plus a 0.5-way configuration – something we can’t recall coming across before. Firstly, there are two tweeters. A 29mm soft dome handles the signal up to around 15khz, when the 17 x 45mm ribbon tweeter takes over. The idea is to produce detailed highs while keeping a nice, wide dispersion right to the 30khz upper frequency limit.
Add the 16.5cm wood fibre mid/bass unit (the upper of the two larger drivers) and you have a 2.5-way design. The 0.5-way takes the form of the lower 16.5cm bass driver fed through a simple analogue filter. The main crossover split, at 2.6khz and taking place between the mid/bass unit and dome tweeter, is done digitally. We can’t recall seeing a speaker that mixes both DSP and analogue in its crossover this way before.
There are two amplifiers in each enclosure – one to drive the tweeters and the other to power both larger drivers. These Class D amplifiers are rated at a maximum of a modest 30W continuous output, but can deliver up to 250W for up to five seconds. This, Dali claims, is enough to deliver large dynamic shifts, making the 6 Cs sound far more powerful than the baseline figure suggests.
These floorstanders are nicely built, with slim cabinets made of 25mm MDF and heavily braced to add rigidity. Finishes are limited to black or white vinyl and, on our early samples, the fit is spot on. The company has added some nice touches, such as the ability to change volume by moving your finger on the front edge of the top panel. The volume level is shown by a row of bright LEDS below the bass driver.
While the Callistos can accept a wired single-ended analogue signal directly from a conventional preamplifier, they aren’t intended to be used in that way. To get the most from these speakers, you’ll need to buy Dali’s Sound Hub, a preamp that connects to the speakers wirelessly, at an extra cost of £549. Transmission between the two is done at 24-bit/96khz and the company has taken much care to ensure low latency to avoid lip-sync issues with video sources.
Covering all bases
The Sound Hub offers a range of inputs, from two analogue options in the form of stereo RCA and a 3.5mm jack to a pair of opticals and a coaxial. Aptx HD Bluetooth is also here, and – as if to cover all bases – the Sound Hub has analogue stereo and a subwoofer output. You could use it as a conventional wired preamp, though that defeats the point of the Callistos.
Look at the Sound Hub’s back panel and you’ll find two blanking plates for add-on modules. At the moment, the only one available is a network and streaming board that uses technology from Bluesound. Spend an extra £459 and the Callisto 6 Cs can be integrated seamlessly into a Bluesound ecosystem, as well as enjoy network streaming and in-built streaming services.
“To get the most from these speakers, you’ll need Dali’s Sound Hub (£549), a preamp that connects to the speakers wirelessly”
The Sound Hub's plastic casework lacks a bit of substance, but the simple, classy appearance appeals. The Hub comes with an uncluttered remote, but the digital volume display in the middle of the smooth rotating volume control is a pleasing touch.
For some, the Callisto 6 Cs plus a Bluesound-equipped Sound Hub could be all the hi-fi they need. A traditional separates system has no chance of matching the neatness of such a set-up. While the Dali isn’t truly wireless – you still have mains power going to each of the speakers and the Hub – it’s notably tidier and more flexible in placement than conventional passive alternatives.
We place the speakers around a metre from the back wall and fire them straight ahead, rather than at the listening position. This is how Dali designs its speakers to be heard, and it helps with dispersion and soundstage width.
We start with Bluetooth from our Apple iphone 6S Plus, and are impressed. The connection is quick and fuss-free, while the presentation is pleasing. Obviously, despite the use of aptx HD, the overall sound lacks the insight and dynamic subtlety we would expect from a quality hi-fi source, but the Dali package still manages well enough to keep us listening. Despite that modestsounding power output, these speakers are capable of filling a large room.
Switching to the line-level input and using our Naim NDS/555PS music streamer improves the performance massively. The speakers sound more transparent, tracking dynamic nuances with the skill of quality separates.
We play Orff’s Carmina Burana and are impressed by the control and composure on show, as well as the grip at low frequencies. Bass is delivered with precision, agility and texture. The Dalis image well too, layering an expansive soundstage with focus and care. Tonally, things are nice and even. Dali’s speakers don’t tend to be shy at high frequencies and that continues to be the case here.
The dome and ribbon tweeter array produces such an insightful and refined sound that even harsh recordings remain listenable. The Callistos are revealing enough to show up flaws in recordings or source components, but don’t go out of their way to emphasise shortcomings. But when we try the Bluesound module fitted to our Sound Hub sample, that transparency turns out to be a liability.
We are impressed by the way Dali has seamlessly integrated this technology into the Callistos. The Bluesound app offers the user the option to stream from a NAS unit connected to their network or listen to the many millions of tracks available from the likes of Tidal.
It’s a useful addition to the package and, at £459, represents decent value for its features alone. Bluesound’s Node 2i, our favourite affordable streamer, uses similar technology and has the same features, but for an extra £40 cost, and the added clutter of another box.
Our issue is that the module isn’t good enough to show just how capable the speakers are. If you buy the 6 Cs and the Sound Hub with the Bluesound module as your main source, you’ll miss out. The presentation is balanced, full-bodied and refined, but it doesn’t have the finesse or expression these speakers deserve.
We feel the same way about the Hub’s digital inputs – the sound through these fails to excite similarly. It’s neat and detailed, balancing the frequency extremes well, but it’s also a little ordinary. Dali has a reputation for excellent speakers, but the electronics side of this package needs to improve to get the best from the Callistos.
None of this stops the Callisto 6 C/ Sound Hub combination from appealing. It may not be uniformly excellent, but its performance through the line inputs is terrific, and the convenience of Bluetooth and the streaming module cannot be denied. For a performance close to that of premium separates but with reduced clutter, there are few other alternatives.
“While The Dalis aren’t truly wireless, they are notably tidier and more flexible in placement than conventional passive alternatives”
The Dali Sound Hub connects wirelessly to the speakers