Forgive me for belaboring the obvious, but be sure the 60s are set to "large" in your receiver's speaker menu. If you're already there, disregard the above.

While it's true that the 60s have a decent amount of bass, if you are used to hearing a sub integrated with them, without the sub they can sound pretty weak. I don't listen much without the sub anymore simply because I'm used to getting that nice low bass, and would miss it were it absent. No big deal.

Jack

"People generally quarrel because they cannot argue." - G. K. Chesterton