I recognize that performance is not necessarily the main concern for some customers but there are a number of valid reasons to utilize the BP-18 in the Balanced mode:
BP-18 Balanced Circuitry Explained
Bryston has been able to make significant improvements in the new BP-18 preamp circuitry. The major contributor is the fact that we can keep a fully balanced signal path throughout the input to output.
I cannot stress this enough.
The inputs are also a new design.
The output circuitry is also a new design. If we had a single-ended output on the BP-18 or use an adapter, it will give you the same performance as the balanced output, but the problem will be the single-ended connection from preamp to power amp, you would lose all the benefits of maintaining a balanced circuit path.
In the past, a fully balanced signal path was difficult to achieve because you would need a volume pot with 4 tapers. With the volume control chips, this is no longer an issue.
The new design does have a slightly better lower noise floor than previous designs but it’s much better at suppressing common mode noise.