New cables - To judge now or after burn in period?

I am in the midst of auditioning a host of Siltech speaker cables (Siltech Legend 380i & 680i) and interconnects (XLR and RCA - Siltech Legend 380i). Needless to say, they are quite a bit more costly than my existing QED cables (QED Genesis Silver Spiral Bi-wire & QED Signature 40 interconnects).

The Siltech cables are highly recommended by my distributor and seem to be well received by the audiophile press. However, doubts arise as upon trying them at home they do not sound as dynamic as my existing QED cables. While the highs are more resolving and I am hearing things that I have not heard before, the bass seems constricted and the music does not make my feet tap anymore.

Is that because the cables are brand new and have not been burnt in as yet? Or is it because there is no synergy between the cables and my particular system? Or is it a bit of both? If it is a burn in issue, how many hours of burn in is required before I should make a judgment as to whether I prefer the sound of the interconnects and speaker cables?

All inputs or observations are welcome.