I have a Creek OBH-21SE, but am looking to sell it since I've upgraded to a Talisman Audio T3H. Decent class-A headphone amp and you can probably find a good deal on a used one. From what other people have mentioned in Korea, it is a quality headphone amp, but not worth the list price. I would probably agree, if I was capable of designing and building something more complex than a CMoY.
The enclosure is non-obtrusive; it complements any stereo system with a generic brushed metal face and black body. The only complaints I have about the build are that the philips screws in the back were quite short and bent out of shape when I took a look at them. Someone also mentioned to me that they didn't spend a whole lot of money on the parts. Perhaps it could be improved modded, but I've never seen anyone attempt it.
In terms of sound, I haven't had that many other amps to compare it with other than the Pro-Ject Headbox, Yamaha computer speaker jack, Creek 4240SE integrated amp, and my current T3H. What the OBH-21SE excels in (in terms of sound) is absence of noise, two 1/4" jacks (for your listening partner...), controlled bass, and it's slightly warm midrange. On the negative side, the treble wasn't smooth and often shrill and lacked overall clarity in busy orchestral passages.
I was using HD650's listed in my sig when I tested these various amps. The source was M-Audio Transit USB or Sony DVP-7700 + MSB Link DAC. I mostly listened to classical genre CD/FLAC files. Hope this helps.