Line conditioner...

There is a slight hum at the conditioner closer than 2 feet

If that's from the conditioner itself it is likely to be mechanical, should just be a matter of finding the right screw to tighten.

Have you tried the same test without having the conditioners in the circuit? I'm genuinely interested in understanding what these things do that the manufacturers of our amps don't consider worth doing in their own power supplies.

@ mikeydee,
Absolutely! I have had great result from my Inakustik conditioner. Which one did you try yet?

I recently purchased a Panamax strip and it definitely helps the sound of my system.  I noticed it right away.  I don't spend a lot of money on this hobby, but I get reasonable sound with a minimal expenditure (Teac AI101-DA (DAC integrated amplifier) into Sony bookshelf speakers.  I am using Toslink from my TV with the YouTube Music app.  It's sounds good enough for me.

Good to know. And that also answers your original question :-)