The former German distributor Sun Audio used to offer a model that was called BPS-25, the ‚S‘ standing for an improved version of the BP-25. They even offered to modify existing BP-25s to the ‚S‘-specs.
In its product life, the BP-25 also received a power supply update, going from the BP-PSR to the MPS-1. With a custom connecting cable, the BP-25 is, as far as I know, even compatible with the MPS-2.
I performed the power supply upgrade to the MPS-1 myself (plug-n-play), while Sun Audio, as the authorized distributor back then, made the S-upgrade on the main unit (I think they replaced a number of capacitors...).
@James, is there an older ‚non-S‘ batch that would benefit from an exchange of a few components?
BTW, I am still happy with my BPS-25 with the MPS-1 power supply.