I too have the C&C BH, which I've used for about a week now. I am relatively new to headphone listening, but have been a high end stereo fan for many years, just to qualify my impressions. As such I don't yet have a wealth of of other amps and a bunch of ear phones to make in depth comparisons.
The C&C BH has superb resolution, dynamics and detail across the range. Additionally it has very good output and I was able to drive all of my phones easily at less than half of the volume control setting. These include iMac/iTunes running at 96k sample rate, Audinst HUD-mx-1 DAC/amp, Cambridge Audio DacMagic paired with Audio Engine N22 amp, Audeze LCD-2 for over ear and VSonic GR07 IEM. Older phones of lower cost include Sennheiser PX-100 on ear, Sony MDR-NC6, and Sennheiser Adidas PMX-680. I found that the adjustment switches (GC= low/hi, LF=off/on, SF=off/on) something any listener should find useful for choosing settings for their given phones ad source to make for the most satisfying musical experience. For the most part, I found the low and off settings were preferable. As for direct comparisons, there was no direst A/B possible as the closest was Audinst DAC/amp running off iMac's USB vs. the C&C BH running via optical cable to Cambridge DAC, or from the iMAC's internal DAC and headphone out. The best combination was the Cambridge DAC and AudioEngine amp, but the Cambridge DAC and C&C BH were a close second and tad better than the Audinst HUD-mx1.
Other headphone amps selling for a good bit more money will outperform the C&C BH in certain areas, such as little more warmth of vocals and a little more control of bass, but I doubt there's a portable amp about the size of a deck of cards (minus about a third of them) that will outperform this one. Throw in the dual phone outs and power and this $99 amp is a steal in my opinion.