I have considered this as well.
Currently my "Logitech Transporter" is the DAC , This also has volume control.
If I went to the BDA-1 then what I considered was what CONSTANT level would I prefer to run my system at, and could I get on with only ONE constant volume......
There are a number of options to do this.
First, Running the "PRO" Bryston amps which have a gain control (note not sure if this is off to 0dB). On the older ST series this is on the front panel, in the SST it is on the rear.
OR use a fixed antenuation interconnect.
These are just thoughts they do mean it is possible BUT with restrictions, IF you were to go down this route I would think it best as a stop gap until a pre amp can be afforded.........
If the BCD-1 could have the firmware updated to give variable output or fixed output option that would be great. ALSO options for fixed antenuation output..........(I run a day and night setting in my system, -15dB for night setting)