@audiosens - solid wires are better for all signal transfers.
Grnated - solid wires can fracture, but I don't move my cables that often
What may be causing your issues is
- the insulation on the wire
- the geometry of the cable.
- type of wire used - the best copper wire today is UP-OCC copper
- or you could opt for solid Silver UP-OCC wire
Take a look at my post on this iink
https://forum.audiogon.com/discussions/have-audio-cables-really-improved-in-last-20-years
However if oyu apparent lack of top end is due to the speaker - there is no cable that can rectify that
If you have any questions just ask
Hope that helps - Steve