Marco,
If you are in need of better bass, I would save your cash and find an amp with those characteristics you require and run the whole speaker from it.
You will have a much more cohesive sound. The UNO already suffers from the sub meeting the horn up high, so I wouldn't make an even larger difference in character by running subs with differing signal chain.
You will be in heaven when you find the right amp.
If you are in need of better bass, I would save your cash and find an amp with those characteristics you require and run the whole speaker from it.
You will have a much more cohesive sound. The UNO already suffers from the sub meeting the horn up high, so I wouldn't make an even larger difference in character by running subs with differing signal chain.
You will be in heaven when you find the right amp.