I had a chance to put the BHA-1 to the test with HD650, HD700, and HD800 headphones at Audio Consultants yesterday. I tested with Bela Fleck and the Flecktones: UFO Tofu and Terry Evans: Blues for Thought, two of my favorite test discs. I had never heard the HD700 before or the Bryston. My ears are still ringing! You know you are having a good time when someone comes by to close the door to the headphone room because you are scaring the normal customers! Yeah it was one of those sessions. This amp is perfect for those phones. It tamed the 650's bass so it was nice and tight and punchy. On the other hand it smoothed out the treble on the HD800 and they sounded better than I've ever heard them.
I compared it to the Pro-ject Headbox SEII and Lehmann Black Cube Linear headphone amps. I switched back and forth between the amps on each track on each CD several times. The cables were single ended. Ultimately I liked the Bryston better than the Lehmann. The Bryston's sound was fuller, richer, more musical and less fatiguing than the Lehmann with all three headphones. I felt like perhaps there was a bit more ambient information being put out by the Lehmann, but it also sounded anemic and unnatural compared to the Bryston.
I never thought a headphone setup could do justice to Victor Wooten's bass, but the Bryston came as close as I've heard to that. With the HD700 and HD800s the experience was more like what I would expect from really good speakers. There was a LOT of synergy between the HD700 and HD800 phones, and neither the HD700 or the Bryston were broken in at all. So I'm sure it will only get better.
The HD650 sounded great too but the other phones were leaps and bounds better. With the Bryston I heard three very distinct levels of performance with those three phones.
I was using a middle of the road source, some very good but not great CD player. At home I'll be feeding it with an Ayre QB-9 at 24/96 material. The Bryston HD800 combo was the best combo I've heard so far. I ordered one. I'll write more when I get it home.