Jfrech,
I take it that you are not unhappy with the sound you are getting; you just want a little "more." Well, there is to me, good news and bad news. First, there is no obvious weak points to your system (good), but that means that there is no obvious means of "improving" it either (bad). The little more dynamics and soulfulness you want may not be easily achievable without a radical change to the whole system.
I personally think that the SME 20/2 and the SME arm are a terrific combination so it is hard to say any other combination would be an obvious upgrade.
However, I do have some suggestions on possible avenues to explore. I agree with Raul that looking into a new phonostage is a reasonable approach. That certainly minimizes the complications of having to make wholesale changes to other parts of your system. There is an incredible variety of available phono stages and the "best" for you is not necessarily the most expensive so do not think that you are limited to looking at something in a certain price range (like the Io) as the only logical "upgrade."
A more adventurous approach would be to consider another amplifier. The liveliness and soulfulness you are looking for might be provided by something like an OTL amp. Atmasphere comes to mind because your BAT preamp has balanced outputs. Good OTLs sound a whole lot more alive and exciting than most other forms of amplification (good SETs also do this, but are limited to use with very efficient speakers). I use a SET amplifier myself, but, my speakers are 99 db/watt efficient and I don't need really high volume level. With more "real world" applications, I like OTLs (provided you can stand the heat).