After looking online, it appears there are different versions of the integrated amp. 1) Has no main amp input and using another preamp is not possible. 2) Has main amp input with toggle switch. 3) Has main amp input with jumpers to output. Which version do you have?
How to hook up a preamp to a Integrated amp
Have a Sim Audio Moon p5 preamp i would like to try on a LSA Statement integrated as described in first paragraph in this link
https://parttimeaudiophile.com/2011/10/25/rmaf-2011-eficion-exemplar-stillpoints-lsa/
https://parttimeaudiophile.com/2011/10/25/rmaf-2011-eficion-exemplar-stillpoints-lsa/