Keep the ARC unit! You will be decidedly unhappy with most other units unless you spend serious money. People have to resist the impetus to change. You wind up wasting a lot of money for minor improvements if even that. If you have money burning a hole in your pocket look at the weakest link in the chain which is usually the cartridge/tonearm or the speakers. Adding subs correctly will make a huge difference as will up grading your speakers. In terms of electronics amplifiers make the biggest difference because they have to interact with the speakers which may or may not be easy depending on the speakers you have. If you can afford room control go for it. That will improve your imaging significantly.
