Congratulations on the Elekit amp!
I think a Decware - The Zen Switch-box might be good for you.
I have a Elekit TU 8340 pp (also a 1 input amplifier) with KT77's and Elekit TU 8500 pre- amp, so I do not need the additional inputs. (Both amp and preamp have all the upgrades possible and are a FABULOUS value for the SQ/Investment, as I am sure the 8600 is...)
Enjoy...