If you are looking to keep your 1.7i for a while then I would concur with those who suggest making the investment in a pair of RELs.
It will not only deliver clean tight bass, it will also enhance your overall lower mid range by revealing more depth and texture within
your sound stage.
I was looking to invest in a new pair of speakers a few years ago. I changed my view on how I was looking to achieve my goal of obtaining better sound. It was then that I realized that I could better than accomplish my goals if I invested in a pair of Subs.
I looked at JL as well but found that the Rels were more Musical - especially using the Neutrik SpeakOn connectors at the
High Level
input to the sub bass system. Although REL makes these cables, Three are a couple of other companies that make upgraded versions.
I still have my Speakers and REL's and have no plans on upgrades..
If you go on the website there is a speaker - sub pairing section. They recommend the T-9I for your 1.7I.
Good Luck