That's a good question. Here's my very limited experience: when ever I get a new piece of gear, it comes to the office first, where I can break it in and figure out how an opportune moment to take it home. So, when the ModWright modded DVD-434 arrived, I happened to be using an AMC CDP feeding a stock ART D/IO DAC. The difference in sound was outrageous. I mean, a quantum leap forward.
At home I was using a Rotel CDP (circa 1995) to feed the P-3A, and honestly, the difference wasn't huge. But make no mistake, the modded P-3A was substantially better than the D/IO (I haven't heard the modded versions of these, but they certainly have their partisans).
I chalked this up to system synergy, and the probability that the D/IO just needed a better transport to get somewhere special. The P-3A just seems to start out much further ahead, so the transport didn't add as much.
One way or the other, I'd rather have all my gear get the ModWright touch. It means that I don't have to worry about getting max performance from a particular piece of gear.
David.