dkinric
Addicted to Fun and Learning
Listening Tests
If you have not experienced a high power amplifier driving the Sennheisers, you need to experience them to know what I am talking about. The character of these headphones changes completely. Bass becomes thundering as if there is a subwoofer in there. Clarity and resolution improves. At lower powers I just find the sound dull and uninteresting.
I have the HD-6XX and I know what you are talking about. Even when paired with the DX3PRO in high gain, although it was clean output, it was not as engaging as I had hoped. I recently plugged them into my Cambridge Audio CXA60 and wow, what a revelation! I have not been able to find any rated specs for this output, I know on many home amps/receivers the headphone out is an afterthought. Not so on the Cambridge. Bass was well defined, overall tone immersive and detailed - improved clarity and resolution as Amir notes.
Obviously CA put some effort into this. If your look at their literature, they claim to put a lot of resources into the electrical design, using all balanced architecture, a very large transformer and designs to minimize interference. In my experience with this amp, it seems to be more than just marketing speak.
So, anyone with an Sennheiser HD-650 / HD-6XX - it transforms into something really special if you can feed it very high power (at least a good bit more than 120 mw). Also, The Cambridge CXA-60 has a very good, very powerful headphone amp (also an outstanding Integrated amp all around).