IMO the Rega turntable will be good choice for your setup and system and will perform and sound way better than your Marantz turntable. Rega turntables start at little less than $1k up to around $10k not including tonearm, cartridge, PSU & phonostage preamp. Any of these Rega will sound better than your Marantz turntable.
Or you can look into a Linn LP12 Majik version turntable package which is an entry level Linn LP12 turntable version or package. Sonically this will be a step up from most Rega turntables.