I smell alot of BS from #3. This kills off any hopes of the chassis blocking off EM/RF Interferences from your mobile phone/dect phones/bluetooth/wireless lan. Is he serious?
This is firmly based in DIY territory.
Some are willing and able to explore what changes do or don't make differences to the performance of their DAC, amp, what ever…
I have found that some tweaks can make impressive changes.
It’s the curiosity to find out, along with the willingness to take a calculated risk.
These 2 factors, curiosity and risk, are where the rubber meets the road, so to speak.
Those with experience in dealing with electronic gee-gaws can significantly reduce the latter (risk) while letting the former (curiosity) go places others may never comprehend.
And it's during these kinds of experiments where you truly come to know what taking responsibility for your actions, truly comes to mean…
As for emi/rfi 'protection' the only way to know is to try it yourself, or have some one(s) perform these mods and report back…
As for me I opt for simplier, less intrusive mods, but if the curiosity is strong enough and I can reverse the mod 'cleanly', well then it can become a no brainer…
JJ