Yes, there are many possibilities. You can go with
- a modular stereo/panning mixer. Like the Sputnik, or the L-1 VC Stereo Mixer
- separate panners like this Doepfer
- even building your own panners using many VCA's :)
- using an external performance mixer (Mackie, Allen&Heath) of which the most have control over panning their L and R
The most cost-effective way is undoubtly an external mixer if you don't need CV panning control over every channel.
If you know that you'll incorporate drums at some point in the 'not so distant future' a 3rd U is a very good idea