This is what I would do first before adding a Chassis IEC socket to your amp (unless you're able to do yourself). Go buy a Furutech FI-15ME AC plug. Install on your fixed cord and I think you will find the results very satisfactory. I've done this to int. amps/CDP's and was amazed how much better things sounded. Very good product along w/the FI-15E IEC connector. Made a wonderful improvement on my Arcam 10 int. amp
Update power cord
I have a Rotel RB 991 power amp driving a pair of Vandersteen 2 ce speakers. t has a captured power cord now would spending a few bucks to have an IEC power outlet installed and upgrading to a reasonable cost power cord make a difference. I would like to smooth out the top end a bit.