Are they truly balanced?

I was wondering if all quality preamps that offer both single ended and balanced connectors are truly balanced designs. I'm pretty sure that the BAT equipment is of this design. But what about those preamps from the other high-end companies?

The reason I'm asking is that I've got an EMC-1 CDP that many people say sounds better using the balanced output. My current pre is single-ended only. My power amp is balanced though. I'm thinking that maybe a balanced pre would make the whole system sound better.

Any thoughts?