Cable upgrades

Happy Holidays to all!

I’m reconfiguring my system and am interested in upgrading my interconnects and possibly my speaker cables, and I was wondering if you could make some recommendations.

I was running Audio Sensibility Impact SE XLR between my Benchmark DAC3 HGC (as a DAC/pre) and my Benchmark AHB2 power amp.  The amp is running bi-wired Kimber Cable 8TC (I think that’s the model #) to a pair of ATC SCM40 tower speakers.  In this setup the bass is tight and the mids are clean - overall I’m quite happy - but sometimes I feel, for my ears, I’d love a bit more openness / brightness in the higher end.

My questions are: would improved XLR interconnects help to open up the top end a bit, without being harsh, and perhaps increase the dimensionality of the soundstage?  Or would I be better off starting with upgrading the speaker cables?  I’ve been looking at the Cardas Parsec level of cable, and could perhaps stretch to the Clear line, pending your recommendations.

Also, one other question: pending the possible move to 2 AHB2s (in mono-block configuration), do both XLR interconnects have to be the same length?  If not, would it cause any timing issues between, say, a 2' XLR and a 6'?

I’d appreciate any guidance.  Many thanks in advance.

Best, JAMES