£45m eh? Well, a fair bit on securing my family's future, esp my children. Thereafter a fair chunk on other worthwhile / charitable concerns and as for the hifi, that Marantz UD9004 SACD/Blu-Ray player looks like the mutt's whatsits.
I'd probably go back to that high-end system I looked at a while back as well - McIntosh MCD201, Sugden Masterclass amp, Art speakers, Dansette turntable...okay, maybe something a bit more high end there too.
I'd probably install a multi-room system for casual listening while pottering around house, stream internet radio and hold a huge disk based storage repository for the CDs when the radio was rubbish (yes, I know, but sometimes you want your own choice not some station's playlist, no matter how many there are!).
The hi-fi would still take pride of place in the listening preferences though, still enjoy the act of physically playing music, listening to LPs, reading sleeves, booklets, etc. Just more of a connection there.
Likely there would be a music room or two and probably under lock and key to keep little fingers at bay from daddy's toys!