Can I tweak L-R balance by differntial biasing?

I agree with the Almarg....

Depending on how "desperate" you are I see four possibilities.

1) Try Rrog's ideal of changing your room. (Probably the hardest to do if a relationship is involved).

2) Add a preamp with balance control. (Probably the hardest on the finances).

3) Add a voltage divider network just before the volume control on the channel that you wish to lower. (Probably the most time consuming).

4) Have your integrated modified to have either left and right volume controls or adding a balance pot. (Definitely the most trouble to restore to original operation).

Practically speaking, kiss channel balance goodbye if you want to use bias as a 'balance' control as you've described it. By rendering channels 'unequal' in regards to signal level, all you will accomplish is the destruction of the stereo image, ie: point source imaging, depth, extension, and low level resolution. You will have the exact same issue you started with, only worse, much worse. A balance control is an attenuator, not a signal reduction.

Mezmo- Great idea. It works!!!

Can't take credit, myself. Had a friend over who's a sound engineer and we were monkeying with speaker placement. Him sitting in the hot seat, he's got me moving the speakers backwards and forwards by tiny increments. "So, what exactly is this all about?" earned me the equivalent of "why, balancing the image, what the hell did you think?" If your room ain't symmetrical, why would you expect your speakers to be? The simplest solutions are often best. Cheers.

You can buy attenuating plugs that are put in between the interconnect and preamp to change the volume of one channel.

Google "RCA attenuating plug".