As good as the Modwright stuff tends to be still its just very hard to do as well as in a stand alone unit. Basically, it breaks down into the advantage of the stand alone unit in having its own dedicated power supply combined with the advantage of being able to physically space these far enough apart to get really good shielding outweighs the inherent disadvantage of having to pay for the case, always one of the more expensive single items on a component budget list.
I'd be surprised if you don't find all the units listed above to be a lot better, and immediately, like it will jump out at you.
That being said however, and this is a big however, there's more variance in the sound of phono stages than most other audio components. This probably is down to the massive RIAA equalization required, combined with the massive amplification, combined with the microscopically millivolt level input they have to work with. Its just very hard to get it right.
I must have brought a dozen phono stages in for home audition when shopping for mine, everything from Lehman Black Cube at the cheap end to a Linn and Audio Research at the high end with stuff like EAR in the middle and a whole lot more. A lot of these were good enough I could see people being happy with them but the range of sounds was extreme.
So yes you will (not can, will) get significant improvement, but just need to be careful in order for it to be the kind of significant improvement that you really want.
