Current mode vs voltage mode

Will some kind audiophile, in relatively simple terms, explain the difference between current mode and voltage mode signal transfer.

The reason I'm so interested is I own a Halcro amp/preamp combo which sounds much too thin when connected with high quality XLR voltage/standard interconnects. However when I use the unbalanced current mode connection (with standard high quality RCA cables) between amp and preamp it sounds much more musical and the lean qualities near-completely disappear.

Thanks for all thoughts in advance

Brian