Concurrent use of balanced and unbalanced outputs: Lamm L1

Is there a foreseeable issue with using a balanced and unbalanced output for a biamping? My specific situation is using a Lamm L1 preamp for "main" speakers along with two powered subwoofers which have line-level (both balanced and unbalanced) inputs only. My current hope is to use an RCA-to-RCA cable and an XLR-to-RCA cabling (or possibly a Purist Audio Design XLR/RCA adapter) from preamp to amps to avoid a gain mismatch. I have emailed Lamm early this week without response yet and will try again soon with another address. Thank you.