Pros: Overall sound, bass impact and control, lively mids, non-fatiguing highs
Cons: Some usability flaws
DAC OCU(B) 1866 — very interesting portable DAC/amp combo from Russian manufacturer Myst.
Things I like:
— Nice look. As OCUB is made in small quantities, it uses stock case, but case is fully aluminium, and fits perfectly in hand.
— Great connectivity: you're getting USB, coax and optical ins, and in B version even bluetooth. So, you can use almost every DAP as transport
— It has line-out, so you can easily use it with serious amps (btw Myst have few of them)
— Really great parts inside: multibit DAC chip AD1866 from Analog Devices, AD8610 amp, OP275 as buffer. Nichicon KZ and Sanyo OS-CON as capacitors, Neutrik plugs, ALPS as volume control
— Nice measurements: SNR 110 dB, DD 95 dB, russian document about measurements is here: http://ozvuke.pro/index.php?act=attach&type=post&id=2605 (it's easy to understand it)
— Frequency response: 0 Hz – 20 000 Hz. Yep, really 0, OCUB plays sub-bass greatly, if your headphones can reproduce it, you'll get it.
— Tight impactful bass. MyST used really unusual multibit DAC (is it the only multibit portable DAC?), and it gave it's benefits. DAC sounds very musical, especially in low and mid range. It shows best advantages of multibit technologies.
— Great representation of artists emotions. Mids are breathing with passion, reproducing almost all nuances of performance
— Really good soundstage an imaging. Instruments separation is also nice.
— Highs are little bit recessed, compared with regular delta-sigma DAC, so sound is non-harsh and not fatiguing
Things I don't like (a little bit)
— Some usability flaws (e.g. you can't see, how many power left in battery), so manufacturers suggest "6 hours of listen, 6 hours of charge)
— Sometimes I'm missing bit some highs (but not often)
— Slight hum on most-sensitive IEMs (but not very big, I can live wth it)
— Price is on the higher side, it's sold on Amazon.de under Tento trademark for EUR 599,00, so it's not very budget solution. But it's an unique device in some ways, so there is no alternatives
— High output impedance. It's 10Ω, so there may be some problems with multi-driver armatures. But I've tested it with my Ambient Acoustics Am6 (6 drivers, as you can easily guess), and didn't find sound degradation
— Some more power would be nice. OCU(B) delivers 120 mW, it's enough for almost all headphones, but some top-end cans wants more power. Luckily MyST have really great amps