I've had some time to listen to the BHA-1 as a preamp. It is running single ended through xlr female to rca female adapters and to my amp which is a Hafler 9500. The rest of the system is an Emotiva ERC-1 CD player and Totem Forest speakers.
This is the first time in a long while that I have had SS preamp. Previous to this I using an updated Conrad Johnson PV-5 and before that an Audio Electronic Supply AE-3 preamp. I have had other SS pre-amps in and out of the system for periods of time including a Hafler 915, Mac MX-118, and the preamp section of my B60, but have always returned to a tube pre-amp.
The bass on the BHA-1 is great; deep, punchy and full. The upper midrange and lower treble seem somewhat reticent, sterile and dry. Tonally, the vocals are accurate but recessed and without as much presence as I'm used to. This also goes for the lower treble.
The sound-stage is deeper than it is wider. There is nice layering and sense of depth. The music seems to come from farther back on the stage; the sound emanates from the plane of the speakers back instead of out into the room.
I mentioned a dry sound earlier. The preamp is very accurate, quiet and fast; almost too fast. The notes disappear almost as fast as the are heard. There is no decay or shimmer to the music. All the notes and detail are there, they just don't hang around.
These traits are not evident to me when listening to the BHA-1 through headphones. Perhaps the fact that the output to the amp is being converted to single-ended has something to do with it although I've converted inputs to balanced amps (2b-lp pro) to single ended and haven't noticed this before.
One other note regarding the volume control and this has been mentioned in other threads: It is not linear, there is what I'll call a flat spot where there is very little gain from about 10 o'clock to 2 'o'clock.
Honestly, I'll going to keep the BHA-1 for use as the outstanding headphone amp that it is and see if I get used to its qualities as a preamp.
