Ik wlll get you more power. It is going to pull a lot of current and the psu is going to get quite hot.
Offboard sounds like a good idea but I am not sure how much current those tracks are rated for, how much they can take and for how long they will last. For that reason, I have decided to stick to specs. and to use 1.5k.. But of course, with 1k you are going to get more power and arguably/perhaps "better sound". I have heard Kelvin's, using 1k, and I must say it sounds very good to me. No way to A/B compare until I am done with mine.