I recommend those who are addicted to tube sound or are curious to stay far far away from the C&C TU. The prospect of draining your wallet of a few hundred dollars is all too easy after reaching drunken musical bliss after listening to this little leather covered flask.
In the box: Wooden box, velour carrying bag, manual, AC adapter, leather sleeve
4 switches on the back:
TU: Turn the tubes on and off. Said to be identical to the C&C XO. Sounds more analytical and harder off. Fuller, more liquid, warmer on.
GC Low and Hi: More impact on high impedance phones. GC cannot be used on low expedience.
LF: Bass booster. Emphasizes low-mid bass. Still defined but can overpower mids on some songs.
SF: Seems to slighty increase volume, increase perceived soundstage. Little affect on Hi GC.
Tested with: RE0, PK1, K701, K501
Bass: natural, defined, slightly more bloomy than solid state, but not boomy. Extented bass impressive on Wutang's "Wolves."
Midrange: "They call me the velour fog," as Futurama's Zapp Brannigan once boasted before being booed off a karaoke stage. This is where the TU really shines with the tube magic. Vocals sound natural and silky. Hiroshima's 1979 recording of "All I Want," a very analog sounding album. Singers voice seems to hang in space and float like a velour fog with both the RE0 and PK1.
Treble: Compared to solid state, the difference is subtle but noticeable, especially over time. Compared to the E3 for example, the highs are sparkling but without the fatiguing metallic highs and sibilance. Tight, airy yet slightly liquid and not rolled off.
Soundstage: With the RE0, percussion seems to come from outside of the head, excellent separation, clear imaging. Stunning 3d effect with K501.
Pros: Not overly tubey, excellent build quality, clarity, many settings suitable for many headphones, silky smooth mid, no sibilant treble, solid state sounding bass, not overly tubey, tubes not hot, no real competition, dark-no humming other than microphonic high pitch. Enough juice to power demanding headphones to a louder volume than I could listen to.
Cons: Not overly tubey, microphonic-not a problem carrying it around unless it's tapped, or switch moved, takes 30 seconds to diminish. Please note that this is not noticeable when listening to music at a reasonable level. The one caveat to this device is its microphonics. If you think this is going to bother you it probably will if you are doing critical listening while moving around a lot. RF interference.
Recommendation: The best of tube and solid state. I personally don't feel too comfortable carrying it outside or on the subway, but the benefits of an amp are minimal in a noisy environment or for background listening. It fits the bill perfectly for plane travel, and setting up a satisfying system away from home. This is especially good for analytical and “boring” headphones to add some smooth flavor and bass.
You probably will like this if you listen to: Jazz, classical, trance, acoustic, vocals
You probably would be better off with solid state if you listen to: rap, rock, house etc.
Diminishing Returns: Is this worth 30 times the price of the Fiio E3? It is clearly not 30 times better, but I would buy it again for the subtle tube magic that makes precious time listening to music just that much more valuable and satisfying. It's not an amazing bargain, but it holds its own in a crowded marked of portable amplifiers with a unique sound, nice build quality, and fun features. It certainly makes the neutral and dry RE0 fun to listen to while retaining enough realism and clarity to be drawn into the music and make the components disappear.