Firstwatt B2 functionality?

I missed the bus on the Firstwatt B2 by many years. Does anyone know of a similar DIY approach for bi-amping using different amps. I’d like to find a preamp/buffer to use with my tube amp and F5-turbo V3 monoblocks driving a pair of LX mini via the analog crossovers.

If anyone has a B2 that they would like to sell, I’d be interested in talking.