I don't like the sound of my system. Help please.

" Apparently its implementation of Class T amplification results in its being a powerful generator of RFI (radio frequency interference)"

Excellent point!

RFI noise from an older switching amp is quite possible. Physically and electronically isolating it as best as possible can only help.

"Sell the speakers to me. That's my suggestion. How old are they? That may not help your sound, but it would help me:)."

Then you would just be going from one mediocre speaker to a slightly better sounding mediocre speaker. Set your sights higher......

Shakey

I would let go of the Vandersteens. I'm not impressed with those. Rolled off highs, and a emphasized lower midrange/upper bass. This is my opinion, of course.

IMO the ARC 150.2 is the problem. ARC digital (switching) amps all suck, and sound like you describe! They do not have a good following.

ARC is best known for FET/tube, and pure tube preamps and power amps. Everything else they make can not compete with alternative brands and should be avoided!

Everything else you own is very good for the money, and I have heard them all over the years.

I heard a current generation ARC switching amp recently at Lyric in NYC. Brief audition but sounded promising.