It is not a dac. Preamp only. Use dac in front and a headphone amplifier after it. Coast is around 1k.
Haffler HA 75 IS A VERY GOOD MATCH WITH Neumann NDC 20. Actually, it will rock your socks off and give you lots of fun factor. Also serious high end if you like live sound. You will not expect what you will hear before lifting up your headpones the first time. Often it is like being in a small concert hall . You will get this experience with about 50& of your album/trecks. Very good combination this for listening to hard rock, rock, jazz, electronic. Not good with classical music. This is my personal impressions. Do not drink alcohol when listening with this preamp active because you will need the insane rocking feeling more and more and turn the volume way to high and damage your hearing. Serious.
Personally i like to have the tube volume at max, the x-feed at max. Then use the x-feed button on/off for testing and listening. It is recommended to have a headphone number two at hand. Because Neumann/Haffler not will work well on all album/tracks. I then switch to Sennheiser HD800 WITH GREAT RESULT often. Closed and open headphone is nice to have at hand when the track is not so good match. Expect to use the buttons on Haffler quite a lot in the beginning, but after a while it feels natural to have an interactive listening session. Muscle memory. Seems like Haffler works best with studio and neutral headphones simular to Neumann and HD800.
I am not an experienced classical music listener. To me the Haffler HA 75 works really good with HD800. Adjusting the tube volume to best fit the violin or cello or big orchestra.
When listening to rock and jazz i often turn on the loudness switch. Not all the time though. The bass switch is really hard on most tracks, but can be useful to live up recordings with no bass or headphones with little bass like HD800. YOU GET THE picture, Neumann is fun, very fun and good, but can be dangerous. Then, switch to a headphone like HD800 for more relaxing listening.