This review page is supported in part by the sponsors whose ad banners are displayed below

This could be useful in commercial applications where more than two speakers are deployed to cover various locations in an odd-shaped asymmetrical floor plan. Yes, I hadn't yet mentioned that the Opal-air4 caters to commercial venues like clubs, restaurants, function halls, gymnasiums, churches and sundry. The inspiration for that probably came from Mark & Daniel's Shanghai side business as restaurant renovators who work in classy compound marble. The maximum number of speakers that may be mobilized to serve one venue with a single wireless signal source is four. Hence the model designation Opal-air4. Price per unit indicates that you can purchase just one if that suits your commercial needs.

Snugly mounted on the back is a NuForce black box known as Air DAC receiver. Already connected to the receiver are a pair of RCA connectors feeding analog signal from the DAC to the internal Tripath amp and a 6V DC power wire to run the NuForce wireless module. On the Mark & Daniel website a friendly reminder urges us not to unplug these wires to avoid unexpected damage. That applies to playback using the DAC input mode. Unaware of such warning I did unplug those cables in RCA input mode to see whether that would improve the sound. No pops, no damage.

Perhaps I should deal with my area of expertise before I plunge my head into the wireless porthole? The bi-amp module is based on the TA2022, one of the higher output Tripath chips once favoured by DIYers and budget-priced T amps like the Topping TP-60 and Little Dot T-100. It offers 90wpc stereo power into 4 ohms at 0.1% THD+N. Mark & Daniel employs one stereo chip per speaker for the obvious sonic formula of higher power + tighter control = improved performance. One perennial question about Tripath amps and Mark & Daniel speakers has always been whether these tiny lightweight amps can really drive those heavyweight Mark & Daniel speakers with their mean-looking Super Xmax woofers thumping air at ±7.5mm linear excursion. My answer to that is an absolute affirmative capital-letter YES! I have been for years enjoying such odd but infallible combinations in no less than three setups.

First there's my daughter’s desktop system with a KingRex Headquarters HQ1 headphone/preamp driving a pair of Trends TA-10.2 bi-amping the Maximus-Mini. It seems quite unthinkable for the Tripath TA2024 chips and their humble 15wpc of 4-ohm power yet they put their best foot forward with these heavyweight mini monitors and their unmistakable signature sound. They can play as loudly as my daughter wants for her break dance sessions and K-pop and still sound dynamic and... ahem, musical. The second setup is my 5.2 Bluray A/V system with three Winsome Labs Mouse each bi-amping the front L/C/R Maximus-Sapphires and the forth Mouse driving the surround L/R Maximus-Topazes.

Third is a stereo bi-amp system with a pair of Virtue TWO.2 driving the Maximus-Diamond+.

Both Winsome Labs Mouse and Virtue TWO.2 utilize a more sophisticated Tripath kit known as TK2050. This consists of a TC2000 controller and separate TP2050 power IC for flexibility in tuning and sonic integrity. (For the inside story on the Tripath TP2050 and Apogee DX2200, read the small print on page 4 of the Virtue TWO review.) Both Mouse and TWO.2 in fact configure two paralleled TP2050 chips for more dynamic headroom. The TP2050 power stage is similar to the TA2022 in terms of its 90wpc power rating. What then made M&D co-founder and chief engineer Daniel Lee choose the TA2022 over the TK2050? The answer is simple. The Opal-air4 could not have gone with the TC2000 controller because Daniel needed to design his own preamp to incorporate an equalizer stage for the low/high frequencies and to optimize impedance to match his drivers. His version of the Tripath amp after all is not the usual stereo amp but a dual-mono single-channel amp dedicated to two different drivers in one active speaker.

Another unorthodox feature of this Tripath amp is the use of a more expensive R-core power transformer. Most budget-priced T amps use switching power supplies. KingRex has a more sophisticated toroidal-based PSU as optional accessory which offers noticeable sonic improvements. Daniel decided to go up one notch not only to satisfy his own sonic obsessions but also for practical considerations which minimize electromagnetic interference inside the cluttered enclosure.

When I opened up the back, I was amazed by the interior architectural planning which had managed to cram so many components into such a compact monitor speaker. The Shanghai-made R-core transformer thanks to its non-magnetic gap and uniform balanced windings is not only flatter and lighter than a toroid of equal rating but offers lower temperature, lower noise and better containment of EMI not to mention 90% efficiency. The R-core transformer is secured on a thick L-shaped aluminium bracket for efficient heat dissipation. Joined back to back with this bracket is another L-shape for the power supply + output stage PCB and the preamp PCB. The bottoms of the two Ls jointly support the back panel on which the NuForce Air DAC mounts.

So where is the dandy Tripath TA2022 chip? It’s not visible. It’s located on the reverse side of the output stage PBC such that the back of the chip couples to the aluminium bracket for faster cooling.

Next to the solder points for the Tripath chip are two mini blue trimmers. These I know from the past as DC offset adjustments for the speaker terminals (measured with a voltmeter across the –/+ terminals with power on but signal off to gauge minimum DC currents).

This is typical for Tripath circuits. But you are not encouraged to alter the factory settings because this one is different from conventional Tripath applications and the whole system has been optimized (not to mention that it could be dangerous if the power is still on after the back panel has been removed.)

Likewise for the third trimmer on the preamp PCB which adjusts the <1kHz bandwidth. According to Daniel this trimmer setting will be fixed with glue in future production to disallow any tampering. Judging from what I heard,I would leave these settings alone. They're exactly where they should be already.

The third PCB right behind the woofer looks like the usual crossover network for passive speakers but isn't. The electronic 950Hz crossover is imbedded on the preamp circuit. What this PCB does is HF/LF equalization + impedance matching for the highly demanding drivers. "The entire system has been meticulously calibrated and aligned in the factory and no user adjustment is necessary", Mark & Daniel reassure us.