IMHO the need to use "ONLY" the same brand of IC's and cables is a myth circulated by manufacturers and salesmen.
I agree fully. This is also not the "ONLY" myth associated with IC's, Cables and power cords....there are many more. Why are these myths perpetuated? Probably because some audio components are not robustly designed as to be largely imuune to these minute changes in power or cabling. IMHO, they ought to be. Frankly a good design should not be influenced by miniscule resistive, capacitive and inductive changes of one high quality speaker cable to another. Frankly a good power supply design should not be influenced by dirty power. Frankly a good circuit design (allowing for true balanced and XLR shielded connectors with low output impedance and high input impedance) will usually prevent audible differences between one connector and another.
Instead manufacturers use unbalanced designs (higher noise), cheap RCA cables (often no shield but, of course, GOLD PLATED), amps with very high output impedance (making speaker cables quite influential) and low cost power supplies often relying on cheaply sourced parts that may not have high QC standards.
The end result is that different cables cause no end of sonic wonderment when stictly speaking they should have inaudible or at the most minimal impact.