Triad L3 looks like a 3 channel active ground design. The ground is driven by a 3rd channel.

http://www.amb.org/audio/mini3/
read the section on "Precision virtual ground reference"

also: http://tangentsoft.net/elec/vgrounds.html

Supposedly 4 channel (balanced bridged) > 3 channel > 2 channel. There's too much variability between amplifier models and it can be argued that the benefits from 4 channel come from more power. My anecdotal observations are that balanced balanced bridged sounds more open and spacious and controlled with certain harder to drive headphones. Maybe this is why that ALO unit sounds so good, but it literally is the size and weight of a brick.

Even the use of balanced connectors on SE amps such as the Stratus, BA, etc. I hear better bass extension and more micro-detail, at least I think I do.

Some people who have build B22s have said that 3 channel didn't make a difference. I built a simple chip based amp a few years ago, and added a 3rd amp for the ground channel, and I swear this made a huge difference, even with the relatively efficient headphones such as Grados.

while i'm a big believer in line level matching with a DVM and test tone, it does have some limitations.  that being said, i've compared my own B22 to various other B22 builds, all with identical quiescent current biasing, and various pots/attenuators, and personally don't feel the the sonic differences between balanced and unbalanced are worth the extra cost and space when fronted by my BM DAC1.  others with different priorities may disagree.  that being said, i do agree with purrin that balanced does give you a slightly more open soundstage.  i heard this difference in a Bijou amp that i converted from unbalanced to balanced as well, but could not do an A/B comparo like i've done with the B22.  keep in mind, these are only 2 different amplifiers, and by no means an exhaustively formulated opinion.