You have a very good amplifier, and you would need to go some way to appreciably improve on the Elex-R. Why change it? The same applies with your CD player, and the options are thin these days. Rega discontinued the Apollo some time ago, which at half-width size leaves the Exposure XM, various Pro-jects, Leak transport and (announced but not yet released) the Mission transport.
I've tried the all-in-one approach, and I never settled with it. It may have been in part due to me finding the Audiolab Omnia to be disappointing and the hi-fi equivalent of a wet lettuce, but I'm also very wary of combining everything into one box. Your Elex is a beautifully made amp that should last a very long time and will be very repairable if something does fail. A seperate streamer can be replaced if it fails or is no longer sufficiently supported, without upsetting the rest of your system. Personally, I would counsel caution, but ultimately only your pockets, preferences and ears can decide.