There is no empirical data to support this
I tried very short cables and it was bright and irritating.
I tried longer cables of the same type and it sounded very good.
I tried various other short wires with the same effect, bright and irritating.
I put the long cable back in and it sounded fine.
I did this for several friends and they all confirmed what I heard.
How emperical do you have to get to confirm the effect? Have you tried it yourself or just assuming?
I contacted Kimber (a reputable manufacturer) about this and they confirmed that if too short their cables would not sound good.