When asked where frankenwires were to be filed, qusp replied
Originally Posted by qusp
file it under mutants...
...and their amplifiers
There are two variants of what I originally called the SE-BRGD frankenwire. Both start as rework boards. One gets a pair of LME49860 to replace the LME49990 using the simple surgery below. The + and - inputs to the second 49860 are reversed and resistors adjusted so the gain is equal on both sides. The effect of that reversal is to invert the signal on the second leg so it becomes a mono amp, whose differential outputs are ready to bridge one can.
The second variant, more correctly referred to as the BAL-BALM, requires no rework surgery (so could just as well not even be a rework pcb), just the addition of a tiny adapter to mount an opa1632 and leave off the 49990s. Power connection is not as clean as the first variant. It is effectively half a BAL-BAL, perfect for the audiophile with only one ear.