Yes.
Different high-end (and low-end!) gear
can have different sonic characteristics. Two different speaker cables, for example, may have sufficient differences in inductance, resistance and/or capacitance to have an audible effect (more effect on the high audio frequencies, less as the frequency drops) on amplifier loading and the signal reaching the speakers. What I object to is use of outright nonsense to sell gear. Here's an example:
Quantum Tunneling is a process that changes the way a cable conducts signal at the subatomic level, affecting the entire cable assembly: connectors (RCA, XLR, spade, or banana), solder joints, dielectric, and signal & ground conductors are all transformed and integrated as a single unit. By applying a two million volt signal to a cable at a specific pulse modulation, and ultra high frequency for an exact duration of time, we transform the entire cable at a molecular level through a process we call Quantum Tunneling. ... The before and after is startling, with a lower noise floor and improvements in inner detail, air, low frequency extension, and overall transparency and signal speed.
This is pure flim-flammery, an abuse of scientific terminology, and a level of technobabble nonsense far beyond the colourful emotional puffery used to sell (for example) perfume and jewellery.
Imagine if computer or mobile device you're reading this on was sold not on the basis of the speed of the processor, amount of RAM, and size of hard drive -- or even how the case is designed and manufactured to exacting standards -- but on the fact that each circuit board is subject to a precisely-timed burst of microwaves. This transformative process -- which we call Quantum Oscillator Optimisation -- tunes the processor, maximises the RAM, and energises the hard drive to give the computer a startling fluidity of processing, freedom from lag or jitter, and vibrancy of screen colours with visibly higher resolution detail and crispness of both vertical and horizontal pixel lines.
That would be universally laughed at in the IT world -- particularly if a premium price was charged for Quantum Oscillator Optimisation -- and yet in the audio world the same silliness is not only tolerated, it's embraced, and its merits are debated and discussed, and those who point out that the emperor is naked are sometimes dismissed or even marginalised. (E.g., see the fifth bullet point under "posting etiquette" on
http://www.head-fi.org/a/terms-of-service.)