I have no interest in multichannel reproduction, but when Kal shared with me his very positive experience with the dac8 PRO—and then I found out that a two-channel version, the dac8 Stereo, would soon be…
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For his review of the Pink Faun 2.16x music server in the December 2020 issue, Kal Rubinson needed to use a Linux-compatible multichannel D/A processor. A little Googling uncovered the 8-channel dac8 PRO from Okto Research in the Czech Republic, so Kal borrowed one from the manufacturer. He found it to be a great-sounding DAC with an intriguing feature set. He purchased the sample.
In the summer of 2020, Sasha Matson, Mike Marciano of Systems Two Studio, and I were working on a revised version of Sasha's jazz-flavored baseball opera Cooperstown. The original was released in 2015 as a 2-CD set and received some good reviews, including one in Stereophile. But a performance of the opera in Las Vegas in late 2019 required the running time to be cut to 80 minutes or so. Having made those cuts, Sasha decided that re-editing the opera to fit on a single CD would sharpen the work to better fit his vision.
Once we had prepared the new hi-rez two-channel masters, I…
Sidebar 1: Specifications
Description: Two-channel, digital-to-analog converter with volume control, headphone output, 2" × 2.42" OLED display, 7 PCM reconstruction filters, optional Raspberry Pi module, and Apple remote control. Digital inputs: AES/EBU (S/PDIF voltage compatible) on XLR, S/PDIF on 2 RCA jacks and 2 TosLink optical connectors, asynchronous USB Type B, 2 USB Type A host, Ethernet on RJ45 jack and Raspberry Pi module, Wi-Fi via Raspberry Pi module. PCM sample rates supported: 44.1kHz, 48kHz, 88.2kHz, 96kHz, 176.4kHz, and 192kHz via AES/EBU and S/PDIF, plus 352.8kHz, 384kHz…
Sidebar 2: Associated Equipment
Digital sources: Roon Nucleus+ music server; Ayre Acoustics C-5xeMP universal player; MBL N31 CD player/DAC. Ayre Acoustics QA-9 A/D converter.
Power amplifiers: Parasound Halo JC 1+ monoblocks.
Loudspeakers: KEF LS50 and LS50 Meta, Bowers & Wilkins 705 Signature.
Headphones: Audeze LCD-X, Sennheiser HD 650.
Cables: Digital: AudioQuest Vodka (Ethernet), AudioQuest Diamond (USB), DH Labs (1m, AES/EBU). Interconnect: AudioQuest Wild Blue (balanced). Speaker: AudioQuest K2. Headphones: Nordost Heimdall 2. AC: AudioQuest Dragon Source…
Sidebar 3: Measurements
I measured the Okto dac8 Stereo with my Audio Precision SYS2722 system (see the January 2008 "As We See It"). Apple's USB Prober utility identified the Okto as "dac8STEREO" from "OKTO RESEARCH" with the serial number string "000000." The USB port operated in the optimal isochronous asynchronous mode, and Apple's AudioMIDI utility revealed that the dac8 Stereo accepted 16- and 24-bit integer data sampled at all rates from 44.1kHz to 384kHz. The AES/EBU and coaxial S/ PDIF inputs accepted data sampled at rates up to 192kHz. The TosLink inputs were limited to sample…
What sort of audiophile are you?
I think of myself as a critical listener, perhaps a purist, definitely an enthusiast, of music and audio, who enjoys both the journey and the nuts and bolts. I like my hi-fi direct, simple, and personal. Also, I guess I'm a little bit old-school: tube-driven amplifiers with point-to-point wiring; vinyl, preferably early pressings; spun with belt-drive or idler-drive turntables. I listen to digital audio, too—and when I do, I prefer nonoversampling DACs. I like high-efficiency, high-sensitivity floorstanding loudspeakers and prefer them horn-loaded.
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For my audition, I substituted the Leto Ultra II for my reference Shindo Allegro preamp, feeding my Shindo Haut-Brion power amplifier with Shindo interconnects. A 6' pair of Auditorium 23 speaker cables carried the signal from the Haut-Brion to my DeVore Fidelity O/93 loudspeakers. The main source was my EMT TSD 15 N Super Fineline stereo cartridge, attached to my Kuzma 4Point tonearm, mounted to my Kuzma Stabi R turntable, which sat atop the Kuzma Platis 65 isolation platform. For digital, I used the Denafrips Ares II DAC, which Herb Reichert reviewed in the November 2020 issue of…
Sidebar 1: Specifications
Description: Two-channel tube preamplifier with mono switch, "Presence control," and remote control. Tube complement: Two JJ Electronics ECC82/12AU7; two JJ Electronics ECC832/12DW7. "Energy Source Power Supplies": 1 high-voltage 300V and 1 low-voltage 12V toroidal transformer. Inputs: 3 pairs transformer-coupled balanced (XLR), input impedance 10k ohms; 3 pairs single-ended (RCA), input impedance 100k ohms. Outputs: 2 pairs transformer-coupled balanced (XLR), output impedance 150 ohms; 2 pair single-ended (RCA), output impedance 150 ohms. Maximum input level:…
Sidebar 2: Associated Equipment
Analog sources: Kuzma Stabi R turntable & Kuzma 4Point 11" tonearm; EMT TSD15 N MC phono cartridge.
Digital sources: Asus laptop, Denafrips Ares II DAC.
Preamplification: Shindo Allegro.
Power amplifiers: Mytek Brooklyn AMP+, Shindo Haut-Brion.
Loudspeakers: DeVore Fidelity O/93.
Cables: Interconnect: Shindo Laboratory, Triode Wire Labs Spirit II, Furutech GT2 Pro USB cable. Speaker: Auditorium 23. AC: Triode Wire Labs Obsession NCF power cord, manufacturers' own.
Accessories: Kuzma Plastis 65 isolation platform, IsoTek EVO3…
Sidebar 3: Measurements
The Zesto Leto Ultra II looks identical to the original Leto preamplifier that the late Robert J. Reina reviewed in April 2014, although its two 12AX7 tubes have been replaced by 12DW7s. (The Ultra II also has two 12AU7 tubes.) The manual warns against installing the tubes incorrectly, so I made sure that I inserted each tube in its correct socket and, once that was done, I measured the Leto Ultra II's performance with my Audio Precision SYS2722 system (see the January 2008 "As We See It"). There are three gain settings; the manual says to use the setting that…