I just had a chance to slack off from my busy work and tried out the opamps that I ordered but had been lying around for a long time. So now I feel like sharing my impressions on the trials with everyone
Getting straight to the point, my system includes the Essence STX (of course !) and Klipsch ProMedia GMX-A2.1 with Norstone CL400 speaker cable. The songs I tried are mainly Japanese female vocals and J-Rock. And here are the list of combinations I tried.
LM4652NA + 2xOPA2132P
This was my initial setup before I tried anything else. I'll use its sound as the reference for my other combinations
3xLME49720NA
The result was jaw-dropping in terms of surprise. I never expected to hear THAT much of a difference from just switching opamps. The previous setup sounded so muddy and ugly compared to this one. The 49720's were impressive in terms of treble and details. The sound was very, very detailed with the highs not less impressive; it was clear and crisp that I never imagined my speakers were capable of producing such tone. The separation of instruments was another strong point of 49720's where I said to myself that I'd never go back to the previous muddy setup. What's more is that the soundstage was also widened. The bass, conforming to what everyone says, was lacking. However, in that reduced amount of bass I noticed that it became tighter and no longer bloated. With the preamplifier of the speakers I have, this was welcomed and turned into another advantage where I could just turn up the bass level and achieved the same amount but with tighter sound.
It all sounded good except the fact that the vocal was very recessed. I tried listening to other songs with emphasis on vocals and they all sounded recessed. Trying not to make an overstatement here, but it was as if the vocalist was singing behind the drummer. The sound of the cymbals were even more prominent than the vocalist's. This is something I couldn't bare with as it'd ruin one of the most distinguished characteristics of the genres I listen to.
LME49720 + 2xLT1358
Moving on to the next combination as I left the 49720 in the buffer and switched to LT1358 in the I/V section: The very first thing that struck me when I tried this matchup was the forwardness of the mids. The vocal was the complete opposite of what I heard earlier. Other instruments were playing far behind the vocalist. However, I noticed that the sparkling details, the crisp highs, the wide soundstage, and the great separation were no longer there. I'm not saying that they all sounded horrible; it was just that 3 of the 49720's did a really nice job in those aspects. It still sounded pleasant, but couldn't keep up with the previous setup. So I'd say that this setup sounded natural compared to all other ones I tried, but with very forward mids.
LT1358 + 2xLME49720NA
This was the last combination I tried and it now stays in the chassis. What it did was a balance between the characteristics of the 49720's and the 1358's within my preference. It sports the lovely highs, details, separation, and soundstage of the 49720's while keeping everything in balance and positioning the vocalist at the right place.
Conclusion:
LM4652NA + 2xOPA2132P: inferior to all of the setups I've tried
Many people claim that LM4652NA makes a decent buffer, so maybe this was because of the OPA2132P's
3xLME49720NA: nice and clear treble, lots of details, wide soundstage, impressive separation but with very recessed vocals and lacking amount of bass
LME49720 + 2xLT1358: sounded natural with very forward mids
LT1358 + 2xLME49720NA: the great balance of the opamps I tried today
