combining 2 types of speaker cable?

So I replaced some very cheap stranded speaker cable with some good high purity solid core, there are a lot of things I like about this new cabling and in particular situations It can deliver a more to true life rendition than the cheap stranded ever could.... but there are some things I dont like like, the bass, while fuller and more realised, is not as tight and has this fluffy quality. likewise the treble, while more accurately detailed, is shrouded in a sort of light fogginess... with very complex music these issues become a real problem.

The solid cable is 2nd hand and well used so I dont have much hope of these issues fixing themselves with time.

Instead of replacing the cable Im considering adding some extra ’’supplementary’’ cable to this, something high quality (im thinking Litz, to not taint solid core sound with stranded) but in relatively low gauge (18-16AWG) to tighten up the sound... maybe even deliver a better sound than either cable could alone?

Anyone ever try this out?
I tried a few things like this way back 30 years ago, back when I thought it was mostly BS. Soon as I heard a difference though in no time flat I realized what a total waste of time it is messing around looking for hardly anything when only takes one listen to know there's awesome upgrades to be had.

The good news is unlike the cheap crap the expensive stuff they will actually let you bring home and try. So do that. Go listen. Good stuff reasonably priced is out there. 
I  managed to try this without have to spend anything, since the spk cables only needed to be about .5M I took the stock 3M HD650 headphone cable which looks to be about 24awg in litz. stripping the insulation doubling it up six times made 4 decently thick fine stranded litz wires to add the solid core cables.
Sounds great, no harshness at all and tightened up sound adding insane microdetail. It was a not perfect solution, imaging is not a natural, I suspect imaging is strongest area with a single solid core based on what Ive heard so far.