Without getting into cable apologetics and having spent the afternoon rolling cables.
This is a very "YMMV" question.
1. Can you personally tell the difference when you roll a cable at present. Some people can tell nuances between different bottles of exactly the same vintage of wine. Simply because they have aged slightly differently in the bottle. Most cannot. That said, it is not something that anyone looks for (nor can discern) in a $30 quaffer of a wine on release. The analogy isn't dissimilar.
2. It isn't as straightforward as "cheap" vs "expensive". But whether the sonic characteristics of the cable align and synergise with your own preferences and equipment. A modest cable that works well is much preferable than an expensive cable that does not.
3. There is a structured WSET guide to wine tasting and descriptors. We're yet to see a standardised structure for describing what we hear. But it's loosely there.
- Overall impression: Warm, Neutral, Bright, Harsh, coloration and tuning e.g. W / V shaped
- Soundstage and technicalities. Wide, narrow, depth, layering, separation, holographic, resolving etc
- Bass/Sub-Bass/Low-Mids/High-Mids/Treble/Extension
And the list goes on.
My experience is that more expensive cables usually improve technical aspects. Thicker gauge and more expensive cables tend to add a richness and timbre. But this isn't exclusive and sometimes the balance totally doesn't work. And a cheaper cable is preferable.
Back to your question - can I tell the difference. Probably. How much it matters? Cable synergy is usually the last part of the chain. You'll get much better value with IEM's rolling tips (size and type) followed by the IEM/DAP before you touch the stock cable. Most IEM's come with a cable that has been selected for the IEM for certain reasons and changing it doesn't always result in a value for money (if any) improvement.
Addendum: In context I was auditioning cables with a SP3000 and LCD-5 ; not a CFA Vega. All my IEM's currently have their stock cables.
