I'm not sure that you can compare a pair of Cary 300SEs to a Cary 300SEI. The preamp used to drive the Cary 300SEs can definitely make them perform at Class A status. I have driven my 300SEs with a Cary SLP-98L, an Audio Research LS16 and an Audio Research LS25 MKII; the LS25 MKII is by far the hands down winner. The Cary 300SEI may be a nice unit but I would be stunned if it can out perform the Cary 300SEs - Audio Research LS25 MKII combo.
There is one advantage to using the Cary 300SEI, you dont need to spend the $$$ for a preamp.
There is one advantage to using the Cary 300SEI, you dont need to spend the $$$ for a preamp.