With the proper cabling all Krells sound fantastic.But I doubt you will hear a ""BIG"" difference.You will probably never use all of the 700(I just sold mine)anyways.The mono's should suffice
Krell stereo vs Krell mono bloks
Advantages or disadvantages between 700cx stereo or 350mc monos driving Wilson Sophia 1 speakers? The difference in power output and separate power supplies a consideration and shorter speaker cables also room placement of amps and I guess cx vs mc running in cast.I'm not sure if the upgrade to mcx on mono's is still an option for later.