@gochurchgo - the LPS cleans up the sound by lowering the noise from the power supply. Not that the standard one is bad, just that the LPS is excellent.
Ron Sutherland told me that if I was his brother in law, he would tell me to get the LPS for the Insight. I am sure the same applies to the 20/20 although it is $450, probably because it comes in a separate box versus just a board. I’m not sure what kind of cord goes from the LPS to the main box, but I’m sure it doesn’t detract much if anything from the sound, versus it being internal like the Insight.
My change was getting an external PS instead of the internal one in my Plinius Integrated Amp, which has an internally adjustable MM/MC switch. The dealer who sold me the Plinius (used) initially told me I would be very happy with the Insight or the 20/20, and I didn’t want to spend more on the PS than I did on the amp. I was lucky to find a pristine used Insight, but if I saw a used 20/20 back then, I might have gone for it. I guess initially he didn’t want to talk about a PS since I bought th Plinius when all I wanted was a new preamp he thought I would say forget it (which I probably would have). The Plinius PS worked fine, but the Insight sounds way better.
All I can say is that from the second I plugged in the Insight, the difference was immediate. Then I fine tuned the load to match my cartridge and it got a little better. Sorry I don’t have all the audiophile buzzwords for the substantial improvement, I can just say it sounded much better. With every improvement I make, it is hard to say what did what, I just know when I remember a big difference, and when it is subtle if anything.
I can’t say the sound quality improvement with the LPS was noticeable to me, but maybe that depends on your power source, and I use a good power conditioner. I trust Ron, and I am not as sensitive as some of the .very serious Audiogoners. If you decide to ever sell the 20/20, I am sure you would get most if not all of your $$ back for the LPS.