I would to start a list of those who can switch between balanced and unbalanced on their rigs and what differences they hear. Be sure to include your setup mainly the equipment, connectors, mode, and headphone.
Setup: NA Blur
Amp: Balanced Ultra Desktop Amp
Dac: Grace Design m903
Interconnects: Single ended and balanced TRS to XLR 3-pin
How I switch between the two modes is by using the front panel on the m903 to switch between the balanced and unbalanced outputs. I can channel volume match these via setting both to 90dB and saving. I then switch between balanced and unbalanced inputs on the amp by front switch. I have the volume down at zero when I switch so there is no perceived volume difference. I turn the volume up after I conduct the switch and listen to various tracks.
I hear a clear improvement in the bass response and soundstage. It is as if the driver is tightly controlled in balanced mode and a little sloppy and loose in single ended.
I admit I do not fully understand how each signal path is created nor how each stage is processed, but I do hear a difference. It could be that in balanced mode the amp or DAC for that matter is doing more or even less processing than when it is in single ended ( unbalanced mode ). Perhaps those that are more familiar with the electronics in each can describe how the two signal paths differ and whether a specific component / stage could change the sound in the way I describe.
I can say that I have read all of these concerns as well as benefits with balanced amps, but I am more concerned with either concrete measurements of what people hear rather than pure conjecture based on theory. I will see if both Tyll Hertsens and someone from Grace Design will comment on the various topologies of the balanced vs unbalanced issue. Perhaps then we will all understand how the signal may be different along the two paths.
Regardless I can say with certainty that the setup described above in balanced mode does sound tighter and more controlled than when in unbalanced mode.
Be sure to follow the setup template above and describe any measured or heard differences between balanced and unbalanced modes.
Edited by NA Blur - 1/23/13 at 4:07pm