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After making sure the JB system was fully disarmed, I carried out the first round of Diamond+ auditions in the diagonal room which were all centered on A/B comparison. In the weeks that followed (which unexpectedly dragged out into months), I was A/B/C/D-ing all the M&D bookshelf models, namely Diamond+ vs. Ruby, Diamond+ vs. Sapphire, Diamond+ vs. Topaz and Diamond+ vs. Maximus-Monitor. Now the aftertaste syndrome was absent because these speakers demonstrated far more similarities than differences. My mission was to assess the performance of the various sibling models with different partnering amps and how they compared to the Diamond+, the newest and supposedly best of the lot. In the designer's mind, he probably knew exactly why he created them all. But to the general consumers, which one to choose for what amp remains confusing. That became the question I wanted to answer with my limited choice of amps. I'll try to be concise, focusing on the results rather than process. Throughout I used OCOS speaker cables with their Zobel impedance stabilizers for better high-frequency control. Interconnects remained the same.

Diamond+ vs. Ruby
I began with Ruby, the earliest entry model with the lowest sensitivity and theoretically the hardest to drive. Common sense urged me to use the NuForce Ref 9 V2 SE with the Audio Zone Pre-T1 passive preamp. With premium fuel, even the economically priced Ruby performs like a 50/50 front/rear all-wheel muscle car. The sonic merit it displays took the Blue Moon Award from the tight fist of our publisher. Apart from impact, density and dynamics across a wide bandwidth, it had nuance, articulation and a well-defined soundstage. Since its 2006 launch, it might have lost some lustre to be outshone by newcomers like the Sapphire. Nonetheless the Ruby's raw energy and unpolished candor remain remarkable for any speaker at this price and size. That said, it's no surprise that the Diamond+ was the premium, fully loaded updated version of a well-proven super car. Only this went beyond cosmetic updates. The added comfort and luxury went hand in hand with new technology to enhance performance, like a much refined suspension that remains sporty in action yet comfortable to ride. The Diamond+ remained in command regardless of road condition whereas the Ruby sent complaint messages to its passengers with every pothole.

For the statistically minded, with 6dB gain setting on the Audio Zone Pre-T1 passive preamp and its volume knob at 3 o'clock, the Diamond+ could be pushed to extreme SPLs without the slightest loss of composure. The Ruby began to exhibit abnormal diaphragm movements and distortion unless the volume knob was dialled back to 12 noon while I butchered it with the many sudden bursts of bass drums in "Lady General Mu Takes Command" from Dream of an Opera II. If I may digress: this CD has become a valuable testing tool for auditions. The combination of Chinese traditional instruments and Western symphonic orchestra provides an extremely wide spectrum of timbres and textures. Yearning high-pitched erhu and abrasive suona contrasts with sombre celli and double-basses, pointy pipa and plucked liuqin juxtapose with silky legato strings, sharp wooden clicking sounds from the drum sticks cut through the deep vibrating harmonics of the bass drums. "Lady General Mu Takes Command" has a few massively thumping passages where less capable amp/speaker combination are completely at the mercy of subsonic harmonics.

The dissimilarity in bass control between top-of-the-line and entry model was further magnified as the octane level of fuel was reduced. Since the Diamond+ is biwirable, I pumped in two sets of Dared VP-20 amplifiers. Preamp was the high-gain Dared SL-2000A. This turned out to be another perfect match for the Diamond+. Everything I could have expected from a tube amp and nothing I would expect from Mark & Daniel were magically meeting. Okay, so I lied. I exaggerated to make a point. In my Sapphire and Topaz review, I had a first taste of low to moderately powered tube amps powering up these small speakers. They ranged from the 6wpc Dared MP-2A3C to the 60/32wpc ultra-linear/triode Audio Space Nova M-34. The Diamond+ is the redesigned flagship in this league and surpassed my earlier experiences even with lesser fuel in the tank. I never before heard a Mark & Daniel speaker this warm and tender while handling soft music, this tactile yet refined when dishing out thunderous tutti.


Did the Ruby pass the same test? To be fair, it ran off only a single amp to be handicapped. My 20wpc tube amp was insufficient to hold its composure through sonic turmoil. Some might blame the single rear port of the Ruby. With woofers of this kind of excursion, two exhaust pipes might be better than one. Plus, tube amps could hardly compete with NuForce on damping power. Aided by the unfair advantage of bi-amping, the Diamond+ was the clear winner.


Encouraged by the Diamond's unusual tolerance to tube amps, I challenged it with the Audio Zone AMP-ST, a low power, high speed op-amp design that had the Ruby, Sapphire and Maximus-Mini clipping during challenging passages even at normal listening volumes. The Diamond+ got away with my most notoriously butchery recordings (percussions, cannons, Catulli Carmina) as long as I remained sensible. It only showed aberrant bass behavior when close to subsonic harmonics were present.


Just to reconfirm that high-output power reserves work towards Ruby's advantage, I mated her to the Symphonic Line RG3 MkIII preamp and RG4 MkIII monoblocks. Now Ruby swam like a graceful koi in a large clear pond, displaying exotic colors with subtle changes of light and shadow. Speed and rhythm were well paced and movements elegant. While the Diamond+ too benefited from the 150/300wpc (8/4ohms) and 750VA/100,000µF per channel power reserves of the Symphonic Line, there's no doubt that the same benefits elevated Ruby's performance to close the gap. Good old class AB amps built with traditional wisdom of conservatism never become irrelevant. They bring these giant-killer speakers to life.