I would in fact argue against buying these form high end firms and get ones that meet medical requirements.
I fully agree. As far as I'm concerned audio equipment is just as sensitive as medical equipment, yet few seem to understand the impact and even fewer manufacturers comprehend how easily a quality sound can be degraded by emissions from internal power supplies. It is crucial internal power supply and rectifiers are shielded from other circuitry or even better housed in external cases.
Since few manufactures provide power supplies in external cases, I take a peek inside and consider how and where I can add shielding with a grounding wire. I've done all my equipment and the results are simply stunning. Perhaps I should say it is shocking I have been able to make such amazing improvements that were overlooked/ignored by manufacturers.
Some even go so far as to put dummy plugs in unused ports to eliminate the possibility of proving a direct antenna path to circuitry.
Which I have done, and also gone one step further by putting a stainless-steel gauze used for protection against high frequency radiation and low frequency electric fields over ventilation holes. The one I used is made of thin wire that makes very little impact to air flow.
While phono levels are the most sensitive to contamination, so too are CD/Blu-ray readers, and indeed everything all the way up to and including speaker cables. Yeah, I know you're going to add capacitance, but I believe the benefit absolutely outweighs any negative, particularly when you use quality speaker cable and keep the two wires separated rather than encased.
