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This is the 41st in a series of reviews dedicated to the concept of 32Ohm Audio as embodied by the store of that name in downtown Portland/Oregon and described here - Ed.

Reviewer: Srajan Ebaen
Financial Interests: click here
Source: 1TB iMac running OSX 10.6.7 with PureMusic 1.8d5r4 in hybrid memory play with pre-allocated RAM and AIFF files up to 24/192; Metrum Acoustics NOS Mini DAC Octave; Antelope Audio Zodiac Gold/Voltikus, Burson Audio DA-160 [on review]
Preamp/Integrated: ModWright LS-100 with Synergy Hifi tubes
Amplifier: FirstWatt F5 and SIT proto [on review]
Speakers: Aries Cerat Gladius [on loan]
Cables: Complete loom of Zu Audio Event, Entreq USB cables
Stands: 2 x ASI HeartSong 3-tier, 2 x ASI HeartSong amp stand
Powerline conditioning: 1 x GigaWatt PF2, 1 x Furutech RTP-6
Sundry accessories: Extensive use of Acoustic System Resonators, noise filters and phase inverters
Room size: 5m x 11.5m W x D, 2.6m ceiling with exposed wooden cross beams every 60cm, plaster over brick walls, suspended wood floor with Tatami-type throw rugs. The listening space opens into the second storey via a staircase and the kitchen/dining room are behind the main listening chair. The latter is thus positioned in the middle of this open floor plan without the usual nearby back wall.
Review component retail Breakdown: $349.95
Remote control for the resident samurai?
Take that. "We just started shipping the new 2011 edition of the Music Streamer II+ and I wanted to give you a heads up. A copy of the preliminary literature is attached for your reference. As you have shown inclination in the past to rise to the challenge, I wanted to see if you wanted to consider reviewing this? In my opinion if there has ever been a giant killer from HRT, this is it and by a large margin. I spent almost 4 months working on this and from a measurement standpoint, nothing this side of $3.000 touches it. I think it sounds pretty good too but I will leave that part up to reviewers like yourself and others." - Kevin Halverson
With that glove on the floor I just had to pick it up. Bad habits die hard. Glancing at the poop sheet I saw a 400mA USB-powered 24bit/96kHz device using asynchronous* (master mode) transfer protocol. It runs native Audio Class 1.1 drivers for instant plug 'n' play happiness. Full-scale output is 2.25Vrms. There's a 100Ω Zout, S/N ratio of 115dB (DC to 30kHz) or 120dB A-weighted and 200MΩ isolation between full-size USB input and RCA outputs. The highly spec'd Streamer II+ in the oval box of the preceding iStreamer measures all of 5.6 x 2.3 x 0.875". That's just big enough to include sample-rate confirmation for 32, 44.1, 48, 88.2 and 96K via a cluster of tiny pin-prick LEDs on the input side.
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* For an adaptive mode device, the host (computer) is what 'drives' the system. The timing of the data and hence clock is delineated by a pair of events, SOF (start of frame) and EOF (end of frame). Here the DAC simply follows these timing events and adapts its local clock to mimic the inbound one. The converse approach is asynchronous transfer. Here the clock of computer and converter are independent or asynchronous. For this system to maintain relative synchronization the computer at the request of the DAC sends a feedback value that describes if it is getting ahead or behind the DAC's clock. Neither condition modifies the actual clocks. Rather the computer modifies the data payload size of the next packet(s). If the computer is running faster than the DAC, the tendency would be a data overflow in the latter. So the DAC's feedback causes the computer to reduce the number of samples in the next group of frames, keeping the two within the narrow window of neither running out of samples nor having more arrive than can be clocked out by the DAC's local clock. The opposite occurs if the computer is running slower than the device. Then the feedback value sent by the DAC causes the next frame of the computer to send a larger packet.

So, the popular well-reviewed Streamer II+ had undergone a cosmetic and performance overhaul at the über-value sound clinic in California. Apparently there they don't know of 'no broke no fix'. Even so the mini remains designed & made in the US and priced at a friendly $349 just like the predecessor. Take that. Would designer Kevin Halverson—you may know him from his Muse Audio brand and early involvement in the DVD-A consortium—shed further light on the what/how of his 2010/2011 circuit refinements?

For the poop under the sheets I'd take photos for the next page. For the bigger picture let's invoke quick PC audio basics. Today's young people have their first encounter with music via MP3 iPod & Co. over a set of bad fashion ear buds. The logical juncture to introduce better quality comes from uncompressed files, better headphones, dedicated headphone amps and digital-direct iPod DACs. HRT has its $199 iStreamer for that (although not portable like the far costlier CypherLabs Solo). Stage 2 of the campaign to introduce better sound to more folks is getting into the PC-fi act. Active speakers with digital inputs (Toslink, USB, Firewire) that are steps above the ubiquitous plastic desktop jobs are one obvious address. Most specialist hifi firms simpy don't go there. But USB DACs are big. Of course for the audiophile virgins we're trying to - um, convert... what cost of entry is a no-brainer versus a no-go?


Owners of a $999 MacBook Air can't be expected to drop another grand on some fugly converter box that still requires tons more stuff to make any sound. Even $500 is a hurdle. That's why NuForce gives this customer a $349 Icon2 integrated speaker amp + headphone output + USB DAC. Obviously such multi-tasking requires clever compromises. Packaging it all for such low stickers means high(er) volume manufacture/distribution than is the norm for specialist hifi.
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