Help with Balnced for Pre and Amp Only

Speaker cable isn't xlr or otherwise. XLR interconnect should lower the noise floor some. Maybe some other changes. Your amp and preamp are designed to be run balanced. You should try it.

Will still help even though your sources are single ended.

Speaker cable change?...not necessarily...unless it just doesn't sound so good in the first place, then you can change of course. As for Balanced making an improvement, yes it probably might, even though your sources are not balanced. All you have to do is pick up some very good high end balanced desing on the net hear and try it!...then you'll know. Then all you have to do is sell what you don't like...easy enough.
good luck

Balanced connections won't necessarily be superior, but the only way to determine that is to try it, with a good cable of course.
MIT does build one special speaker cable design that is made especially for balanced amplifiers, although I've no experience with that. Contact membername = joeabrams for further information; Joe is THE man; he will answer your questions & can get you a great deal on cable should you wish to try this.