I installed an 8 ohm L-pad on the B&C DE-250/2226J left channel and couldn't find a setting that mated with the right. The L-pad channel sounded crisper and maybe 'brighter'. Figured the difference was the .33 cap so I clipped it. Now I could balance the sound of the left, L-pad and right 24ohm fixed speakers.

First confoosion: what accounts for the large discrepancy between the attenuation values of this guys chart: 5.47 R1 and 3.7 R2 and yours: 24ohm R1 and 16ohm R2 for 10dB attenuation with an 8 ohm driver?

Second confoosian: With the L-pad in place on the left channel and 24 ohms fixed on the right w/o a cap, the 2 channels seemed to match with the L-pad reading about 6 ohms for both R1 (terminals 2&3)and R2 (1&2).

Remind of you nude parallel resistors on the beach?