Switching opamps - it's the poor or frugal person's way of upgrading to different amps. On hand I have what were the stock opamps in my Gustard H20 - lme49720's - but I also have the old JRC ne5532's that I took out of a tubed pre. I had previously bought Ti's opa2134pa's and Muses 8920d's to replace the '5532's in the pre. Then I bought the Sparkos for the H20, and now I'm trying out the Burson Vivids. Switching op amps is like being able to listen to a somewhat different amp altogether - they each impact the sound in subtle - or not so subtle ways - and are so much fun seeing how they sound with my gears. Just make sure that all the opamps are compatible replacements for each other so that we don't fry or somehow damage internal parts. I've also found that each of the opamps have a time period where they sound either kind of "rough" or "foggy/unresolved" until they stabilize or smooth out to their nominal sound performance - the discretes taking far longer than the IC based ones. Both the Sparkos and Burson took over 100 hours (or a month or so), they were both either lean and tipped up in the treble (Sparkos), or too upfront/bright (Vivids) when I first installed them. They're both much smoother and natural now yet still very revealing. Happy listening.
Yep, when I used to have a Xonar Essence STX in my PC, I remember opamp rolling. One of them I tried was the LME49720 you mentioned, actually. Changed the character of the sound quite a bit. I remember it being a lot of fun, but then again IC opamps were and are a lot cheaper, and you can get a whole bunch of them for very little money.