Resolved

The pickups in this SML721 are a pair of DiMarzio Fusion Edge. I've had both bitter & delightful episodes with the FE & in this guitar, it's the former. The neck humbucker is especially disappointing; darn muddy & quite pointless for my kind of music / tone. It took me a while to finally replace the pots of these guitar.

Pics: ESP

That's right - pots. The default pots were working fine & required no replacement but they were suspiciously under-performing. I came to this realization after looking at the specs of my guitars with FEs in them. Those guitars did not sport the default pots as I did away with them due to corrosion / oxidation. I bought a pair of BOURNS pots from Davis GMC which are currently the OEM for ESP & they are indeed the rightful solution to this issue.

I asked Beez what could possibly be the issue with the default pots as they were working fine since Day 1. He told me budget pots might sometimes be labelled erroneously like in my case, the default pots might be a 250K version instead of the preferred 500K for humbuckers. That might be the case here & it turned out to be a simple fix. Beez fixed these into my SML521 a few days ago. After hours of playing, I must say that BOURNS is living up to its reputation for being good. As good as GOTOH & CTS, to name a couple which are benchmark brands for this purpose.