theaudioamp,
I'll accept your statement that inverters are basically switch mode power supplies. Still, any piece of electronics has a "sound." Nobody understands what distortion measurements correlate with a particular sound. Ricevs has a longstanding business as a modifier of electronics. He has determined that different materials in wires have different sounds. If you don't want to believe his claims, be aware that there are several of his customers I have known personally who vouch for his claims by being pleased with his mods.
Just because you may not find reliable measurements that explain sonic differences, understand that the educated ear is THE best measurement tool of all, in terms of sonic evaluation. Technicians are still in the dark ages of understanding the human hearing mechanism.
A good medical doctor such as myself accepts the claims of patients when they say that a certain drug causes side effects, even if there are no published academic studies confirming patient claims. A bad doctor is one who denies the validity of patient claims just because there are no studies in prestigious medical journals. Well, I've got news for you--a lot of journals contain false studies that are driven by medico-political agendas. A sincere doctor often can't get his article published because it conflicts with the agenda and business interests of the prestigious journal.