You have already identified that you like your set up - the Kef is a great speaker, however you want to expand the soundstage.
In order to maximize your existing set up and achieve a better soundstage with your max budget of $1,500 the best path forward (as others have pointed out) is investing in upgrading what you already have by:
1. Adding another Vandy Sub.- used - Your adding another L&R diver to the kefs, with a dedicated power source. Expands the Mid/ Low range.
2. Investing in Power delivery. - used, Think of it as another component to your system. Will add detail,Imaging, Depth Texture - maximize your amp preamp performance.
3. Look into upgrading your crossovers/recap etc. - Cleaner, efficient presentation.
And I don't even think your budget is going to cover that, but its a solid move towards getting to be where you want to be.
Investing in different speakers in your budget is a lateral/backwards move that will not solve your issues. You want to make investments that move you forward towards achieving your goals.
Good Luck
In order to maximize your existing set up and achieve a better soundstage with your max budget of $1,500 the best path forward (as others have pointed out) is investing in upgrading what you already have by:
1. Adding another Vandy Sub.- used - Your adding another L&R diver to the kefs, with a dedicated power source. Expands the Mid/ Low range.
2. Investing in Power delivery. - used, Think of it as another component to your system. Will add detail,Imaging, Depth Texture - maximize your amp preamp performance.
3. Look into upgrading your crossovers/recap etc. - Cleaner, efficient presentation.
And I don't even think your budget is going to cover that, but its a solid move towards getting to be where you want to be.
Investing in different speakers in your budget is a lateral/backwards move that will not solve your issues. You want to make investments that move you forward towards achieving your goals.
Good Luck