Now if I can't use bridged 525s or can't find a used 625 that has the most recent updates, I may need to look at other options.Richard, to be sure it's clear, using two 525's in a vertical biamp configuration completely avoids the potential issue that has been raised about using bridged amps in conjunction with low impedance speakers. At the same time, it very likely would provide sonic benefits that would not occur in bridged mode, and I suspect would have no downside relative to bridged mode aside from probably having a bit less maximum power capability (although maximum power capability would still be significantly greater than what you have now).
Good luck. Regards,
-- Al