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Reviewers: Marja & Henk
Financial Interests: click here
Sources: CEC TL5100, Audio Note tube DAC; Philips DVP 5500S SACD/DVD player
Preamp/integrated: TacT RCS 2.0 room control system, modified Audio Note Meishu with WE 300B (or AVVT, JJ, KR Audio 300B output tubes); Moscode HR401; Trends Audio TA-10; Qables iQube; KingRex T20U and Slap
Speakers: Avantgarde Acoustic Duo Omega; Avantgarde Acoustic Solo in HT 2.0 setting; Audio Note AN/Jsp silver-wired; Podium Sound Podium 1 [on loan]
Cables: Audio Note AN/Vx interconnects; Siltech Paris interconnects; Gizmo silver interconnect; Qunex 75 reference interconnect; Crystal Cable CrystalConnect Reference interconnect, CrystalDigit S/PDIF RCA/RCA and RCA/BNC, Y-cable, Crystal Cable Piccolo iPod to XLR, CrystalPower Reference AC-Eur/IEC CrystalSpeak Reference; Audio Note AN-L; Gizmo silver LS cable. Nanotec Golden Strada #79 nano 3; Nanotec Golden Strada #79; Nanotec Golden Strada #201 nano3 [in for review]
Power line conditioning: Omtec PowerControllers; PS Audio P1000
Equipment racks: Two double sets of Solid Tech Radius; Acoustic System amplifier shelf
Sundry accessories: IAR carbon CD damper; Boston Audio graphite CD damper, Denson demagnetizer CD; Furutech DeMag; Nanotec Nespa #1; Machina Dynamica Magic Box; TacT RCS calibrated microphone and software; Exact Audio Copy software; Compaq server w/Windows Server 2003 and XP; iPod; wood, brass and aluminum cones and pyramids; Xitel surround processor; Manley Skipjack; Boston Audio Design TuneBlocks
Room treatment: Acoustic System Resonators and Sugar Cubes; Gizmo's Harley Davidson cap
Room size: ca. 8.0 x 4.70m with open extension to a 2.20 x 2.40m A/V bay and open kitchen. Ceiling height is 2.50m, reinforced concrete walls of 45cm, reinforced concrete floors and roof of 30cm. Room has on one side a large glass bay.
Review component retail: $475

"Let's face it, nowadays there are only two sources for portable use left to us. No more portable CD players; they faded out and don't have an analog line-out. The vintage ones didn't have any battery life better than 2 hours. And keep in mind that you had to carry all your favorite CDs in a bag. Then there was the true pain of changing one CD at a time in crowded places.

"So what do we have available as a source that's small in size and can carry all your music? What we first think of is the iPod. If the music is ripped lossless, you have endless options of enjoying it. One of them is getting an external portable amp with high quality sound reproduction to connect to the analog line out of the iPod via a dock cable. Combine that with high-quality in-ear monitors custom-fit to your ear canal and presto: can you experience the heavenly sound that takes you away to the land of dreams.

"The second source available to us now is the laptop computer. Many travel with their laptop as one of their essential business tools. At the same time they have their music ripped to the hard drive, adding pleasure. Another possibility is to watch movies on the computer. The sound quality of the laptop or even desktop is not that high in quality due to the noisy environment and quality of cheap components used. With that in mind, the use of the digital out via USB is becoming the best connection to a high-quality DAC/amp combo to produce the highest possible sound quality from lossless files."

The above explains why Ray Samuels of the eponymous audio company built a portable DAC/amp. And to be honest, his answer makes sense. The times when a medium carried only a single issue of music are definitively over. Apple's iPod presents an affordable easy 160GB of space to fill with a substantial percentage of a music collection in a lossless format. Unfortunately, the standard firmware is not capable of handling FLAC formatted rips and a real simple firmware hack for dummies is not yet available. Who said Apple was led by an open-minded foreman? But we digress.

Ray set out on a project called The Predator that had "the design goal of a high-quality amp/DAC combo with the best possible sound quality that could be squeezed in the smallest possible custom-built portable chassis." Next, the Predator was designed "for the head-fier who wants nothing short of the best quality of sound reproduction on the go so she can enjoy her music away from home. The Predator can serve both types of people - those on the go for portable use with their iPod or any of the personal digital players; or those at home, as a great companion to their desk top when they listen to their lossless files via the Predator."

When the portable amp/DAC combo arrived at our place, we removed from the small shipping box an even smaller-than-expected device - a black-anodized aluminium casing measuring a mere 7.5 x 5 x 2 centimeters with blank aluminium front and back panels. The minute front houses a selector switch for USB or line inputs, a headphone mini jack output, the line input mini jack, the volume control and finally the mains switch. Great detail was expended on the mains switch. When power is on, the lever is illuminated red. At the back there is the receptacle for the regulated charger, then the 3-step gain selector and finally the mini USB input to receive the S/PDIF signal.

Before firing the Predator up, we were curious to see what's inside the tiny amplifier + DAC combination. Unscrewing the back panel was easy. Here we saw the clever extrusion profile which holds the double-decker PCBs. The next page shows how Ray designed the partly open screw holes. Unfortunately we lacked the right tools to open the front panel ourselves but Ray was kind enough to send along some high-rez images of the innards.

The above image opens to 2000 x 1328 at 139KB in a new window

This revealed Dale Vishay 1% SMD resistors, quality film capacitors and a custom-made volume control. The Lithium Ion battery is neatly sandwiched between the two PCB boards. Ray painted the central IC on the board so as to not give away too much of his design. The huge capacitor on the lower board suggested that we had to take care with burning in the amplifier. In order to have all components nicely settled in, it would take some time.

And time is one of the great features of this tiny package. The amplifier keeps on playing for ages on a single battery charge. In fact, it outruns the iPod's battery life of 20 hours (Apple's figure) by almost 3 times (RSA's figure). Remember, the iPod plays from memory once a certain amount of data is read from the hard disc, then spins the disc down. When the memory buffer runs low, the disc is spun up again to replenish the buffer with fresh music data. So when you run larger files on your iPod, it is not uncommon to have the iPod's battery drain well before the theoretical 20 hours are over. You can play far more lower bit-rate MP3 songs than losslessly compressed ones from one iPod battery charge. Moreover, the Lithium Ion battery in the Predator can handle 500 recharges without problems.

Ray shipped a nice but short iPod dock-to-mini-jack interconnect with the Predator and we used that and the longer Qables Gold interconnect for the first (endless) battery charge of listening. This casual listening was done on the road or at a customer's site where listening to music via a simple Ultrasone headphone blocked out enough background mumble and noise to keep us concentrated on software coding. When the first battery charge had been fully transformed to music, we used the supplied universal power adapter to get new life into the Predator. We only had to look for a US-to-Euro adapter piece from our travel kit. Depleting the battery is not an easy task by the way. You have to keep on feeding the amplifier with a musical signal or else it will go into hibernation. The red light of the mains switch goes off and you have to feed some music to the amp to kick it back on again and drain it - eventually.