Both are very good, but they offer different things.
I find MUSES02 is more intimate and warm. Very musical and lush. Seduces you with the sound. But can seem slightly closed in. Bass impact and tightness could be better. I don't feel bass lines are as propulsive as they could be. More of a focus on tones and textures rather than rhythm and pace. But a lovely sound. Sometimes I feel the weakness in bass and rhythm hinders my enjoyment of the music on certain tracks. But overall one of the best chips I've tried.
OPA627, on the other hand takes a step back, perspective-wise. OPA 627 sounds more open and spacious. It just as musically engaging but not as lush. It is still, however, on the slightly warm side. Bass is there with good pace and quantity. Really drives the music rhythmically. And bass dynamics are very good. I was sometimes surprised when a sudden percussion hit came up. Balance of sound is good, and music has a certain "rightness" to it. Perhaps a better all arounder than the MUSES02.
At least that's how it sounds to me.
IMO, they are on par with each other In terms of SQ. When I swapped from OPA627 to MUSES02 for the first time, I was expecting to be totally blown away. I wasn't. I found that it was more of a sidegrade instead of an upgrade or downgrade. I feel that they are on the same tier with each other as far as musical perfomance.
I know MUSES can be very expensive to acquire for a lot of folks. My advice is if you want to try a chip on the same level of the MUSES but don't want to shell out the big bucks right away, try the OPA627. It's a great chip in its own right and should be on top of your upgrade list.
