I agree with Gregm. It is going to be much easier to install an L-pad at or near the crossover for the woofer. The best place would be immediately after the frequency selecting circuit and before any Zobel, if used. That way you can use the driver's nominal impedance and calculate the values for 1, 2 or 3 dB of attenuation. Or, buy a cheap l-pad from Madisound or Parts Connexion. You'll have to evaluate by ear unless you have the tools to do frequency response measurements at the drivers.
Passive Biamping?
Biamping virgin, never tried it before. Speakers are bi/tri-wire capable, no outboard crossover needed or wanted.
Have four channels of power amplification (pair of monoblocks plus stereo amp, all from same maker and of similar power, if perhaps not exact identical gain), of fully-balanced/bridged design, utilizing balanced input transformers with XLR and RCA inputs.
Preamp is fully-balanced, but has (like many such beasts that provide RCA inputs in addition to balanced XLR inputs) one pair of XLR main outputs and one pair of RCA main outputs.
If the preamp had two pairs of XLR outputs, this would seem easy. Likewise if the amps had daisy-chain line outputs. But alas, like most, they don't. Yet I would like to A) keep the signal fully-balanced all around, and B) not incur the 6dB gain difference that would result from taking both the balanced and single-ended feeds from the preamp. (I've inquired with the preamp maker; unfortunately the RCA outputs cannot be converted to a second set of balanced.)
The preamp (like the amps) is solid-state, and doesn't lack for sufficient output drive/low output impedance, but the input-tranny configuration of the power amps does mean they have a somewhat lowish input impedance at 10K-Ohms, should that imply anything for splitting the feed.
So what is the best path to biamping success here? (No, replacing the preamp is not a good option.) It seems to me this general situation -- biwire speakers and four channels of suitable power amplification all on hand, but preamp lacking two pairs of identical main outputs -- couldn't be all that uncommon, but I've never seen XLR Y-interconnects for sale, if that's what's needed...
Have four channels of power amplification (pair of monoblocks plus stereo amp, all from same maker and of similar power, if perhaps not exact identical gain), of fully-balanced/bridged design, utilizing balanced input transformers with XLR and RCA inputs.
Preamp is fully-balanced, but has (like many such beasts that provide RCA inputs in addition to balanced XLR inputs) one pair of XLR main outputs and one pair of RCA main outputs.
If the preamp had two pairs of XLR outputs, this would seem easy. Likewise if the amps had daisy-chain line outputs. But alas, like most, they don't. Yet I would like to A) keep the signal fully-balanced all around, and B) not incur the 6dB gain difference that would result from taking both the balanced and single-ended feeds from the preamp. (I've inquired with the preamp maker; unfortunately the RCA outputs cannot be converted to a second set of balanced.)
The preamp (like the amps) is solid-state, and doesn't lack for sufficient output drive/low output impedance, but the input-tranny configuration of the power amps does mean they have a somewhat lowish input impedance at 10K-Ohms, should that imply anything for splitting the feed.
So what is the best path to biamping success here? (No, replacing the preamp is not a good option.) It seems to me this general situation -- biwire speakers and four channels of suitable power amplification all on hand, but preamp lacking two pairs of identical main outputs -- couldn't be all that uncommon, but I've never seen XLR Y-interconnects for sale, if that's what's needed...