I think your biggest concern is which interconnect to buy that will work best for your tastes and in your system. It would be helpful to know what interconnects you're using now and what you're areas you're looking to improve upon and you'll likely get some good recommendations here. Once you choose you can try it in both positions and then it's up to you regardless of what we say here.
Opinions
Where is the best place to install a higher quality set of interconnect cables? Would it be best to place them from the DAC to pre or from pre to power amp? I can only purchase one set right now so I will have to use one of my existing pairs which is a couple product lines lower. Thoughts?