Hi Gordon,

I really enjoyed reading your August 2020 article on your top-ten products. I noticed that you included the DALI Rubicon 6 C and B&W Formation Duo.

I’m considering buying either the Callisto 6 C or the Formation Duo. I’m wondering if you have heard the Callisto. If so, how do you think it would compare with the B&W? Any advice would be greatly appreciated.

Kind regards,

Hi Laurens,

Thanks for your note. I have reviewed DALI’s Callisto 2 C and Rubicon 6 C, but never the Callisto 6 C, so I can’t really say how it would compare sonically with the Formation Duo. I haven’t heard any of these speakers for a few years now, so in terms of sonics, the best I can do is refer you to my original reviews. But I don’t think you can go wrong with either speaker you are considering. I loved listening to the Formation Duo, Callisto 2 C, and Rubicon 6 C, and I have no doubt that I’d also enjoy the Callisto 6 C.

Other factors may guide your decision. An obvious one is form factor—the Callisto 6 C is a floorstander, the Formation Duo a standmount speaker.

If you go with the DALI, do you plan to use it with the DALI Sound Hub and optional BluOS NPM-1 module? Do you have any conventional components, such as a disc player or HDTV, that you want to play through the speakers? The DALI Sound Hub has line-level analog inputs (3.5mm and RCA) and S/PDIF digital inputs (coaxial and TosLink), but the Formation Duo has no inputs for connecting external components; you’ll have to buy a Formation Audio streaming preamp if you want to play audio from a disc player or TV with the B&W. On the other hand, if you’re not using external components, the Formation Duo has the advantage of being a complete, self-contained system.

Given the nature of these products, I assume that you will be streaming music to your speakers via Wi-Fi. Assuming that’s the case, there are some very important differences between the B&W Music app used for the Formation Duo and the DALI Callisto 6 C / Sound Hub / BluOS NPM-1 module combo’s BluOS app. BluOS has integrated support for more than 20 different streaming services—many more than the B&W app. Both systems support Tidal, but B&W’s does not have MQA capability yet, so you don’t get hi-rez streaming from Tidal. (You can of course get uncompressed CD-resolution audio from Tidal with the Formation Duo.) The Formation Duo supports Apple AirPlay 2; the Sound Hub / BluOS NPM-1 combo does not, so you can stream directly to the B&W system from an Apple device via Wi-Fi, but not to the DALI setup. Both products support Spotify Connect, but the DALI system also supports Tidal Connect. So with both products, you can cue up music in the Spotify app, then transfer playback to the Formation Duo or DALI system, but with the DALI setup, you can also do this with Tidal.

Do you want to play locally stored music files? With the DALI Callisto 6 C / Sound Hub / BluOS NPM-1 setup, you can load up a USB drive with music, plug it into a USB port on the NPM-1, and play these files via the BluOS app. This isn’t possible with the Formation Duo.

Are you a Roon subscriber? If so, some of these considerations will be moot; both the DALI system and Formation Duo are Roon Ready, so you can stream to either system via Roon.

One last note. Bowers & Wilkins uses proprietary wireless technology to stream music to the two speakers. The company claims that latency (the lag between the left and right speaker) is less than a microsecond—which is hugely impressive. DALI specifies a latency of less than 25 milliseconds for its system, but I can’t speculate how much this affects elements like imaging and soundstaging. The two DALI systems I reviewed performed very well in these areas, and the Formation Duo was superb. With the DALI active speakers, I occasionally experienced momentary dropouts in the connection between the Sound Hub and the speakers—I never had any dropouts with the Formation Duo. Granted, I only had these systems for a couple of weeks each, so my experience may not be representative.

I hope this is helpful, and once again, thanks for writing.

Best regards,

Hi Gordon,

Thanks for your reply. After listening to both speaker systems, I decided on the DALI Callisto 6 C. I found that the DALI expressed more detail than the B&W Formation Duo, with an immersive soundstage that seemed to float (the instruments seemed to hang in space, with great separation). I did find that the Duo speakers had a big bottom end for their size, but sometimes I felt that it was a little too forceful relative to the rest of the music. These differences became even clearer when playing Tidal Masters (MQA) recordings.

Also, the DALI Sound Hub / BluOS NPM-1 provides me with more options.

Thanks again.