I like to use Furman units with LiFT and SMS. I do find they add warmth and clean/quiet mid to treble. I miss them when disconnected.
More importantly is having consistent performance 24/7. I rely on the Furman’s to provide bullet-proof surge protection and (sometimes) voltage regulation. If you are worried about that then of course, invest.
Your mileage may vary, but I do think some units are ridiculously overpriced, as are power cables.
In terms of sound quality, invest in good room acoustics first. Then power conditioners.
Best,
Erik