This headphone amplifier is upgraded from a Creek OBH-11. Its internal circuit has been modified to Lehmann Audio headphone amp's zero global feedback Class-A output stage (that requires a lot of work. see pictures for parts removed from the original pcb and re-assembled board). All parts are genuine and purchased from US distributors.

627 and 637 are the best IC for the headphone amplifiers, they offer natural and deep sound with with great clarity and detail, very neutral and musical, almost no coloration. 627 and 637 have very close performance. They also sound a little different. The 627 gives a soft, rich and refined sound that is easy to the ear. It reproduces much better tones than an OPA2134 does.

Caps in signal paths are upgraded to Elna's SilmicII, Nichicon's Muse KZ series and/or Panasonic's FC series for the first class sound.

Zero global feedback Class-A output stage delivers tube-like natural sounds. AC coupled output protects your headphones if circuit goes malfunction (DC coupled power output without over-voltage protection circuit can damage headphones when it goes bad).

The amplifier has been tested with following headphones using Marantz SA8001 and CD6006 CD players: 

1. Sennheiser HD800, HD650, and HD595

2. Grado RS-1i, RS-2e, and SR325is

3. Beyerdynamic T1, T90, and DT 880 Premium 600 OHM

The item was upgraded from a new OBH-11, it may have small marks from test. Amplifier comes with a power supply, user manual and original box.