Cayin C9
The C9 is the reference portable headphone amplifier of its generation: a $1,999 fully discrete, battery-powered, DAC-less amp with dual Korg NuTube tubes, switchable tube/solid-state timbre, and Class-A/AB operation modes. Headfonics calls it Cayin's most refined implementation of its dual-operation and timbre technology and credits it with revitalizing tubes-on-the-go; MajorHiFi and the long Head-Fi showcase agree it turns any competent source chain into an endgame transportable rig. The caveats are inherent: it is big, heavy, and expensive, needs a separate source/DAC, and battery life drops hard in Class-A tube mode.
Topping L70
The Topping L70 is a desktop headphone amplifier built to add nothing of its own. Bench testing returned 120.4 dB SINAD, distortion products near -145 dB and a frequency response called as flat as needed, and the listening notes line up with that: a neutral signature absent of coloration, very linear, punchy and quick, with accurate vocals and kick drum impact that decays fast without bleeding into the midrange. Power is not a constraint. Measured output is about 7 W into 32 ohms balanced on high gain and 1 W into 300 ohms, enough that one reviewer doubted there is a commercially available headphone it could not drive, and hiss stays inaudible on sensitive IEMs such as the Campfire Solaris. Volume is a resistor ladder arrangement with eight memory settings and a level remembered per headphone output, joined by a remote and 6.35mm, 4.4mm and 4-pin XLR jacks. The complaints are practical rather than sonic: the volume relays are very loud when adjusting level, the menu driven setup is called cryptic and the features are described as not intuitively operable, and there is no negative gain setting, named as the one thing keeping the amp off the top of the measurement chart. Staging is where impressions part, described on one hand as vast and immersive with sounds seeming to reach beyond the headphones, and on the other as true to life in size rather than expansive.
