I have a set of Rotosound fitted to a Precision bass and they do seem pretty dull and muted to me across all 4 strings but all balanced. They're ok but I preferred the Labellas I had on a Pbass I once owned.
On my other Precision I've recently fitted a set of Detroit flats. Like the OP the A,D and G are fine, quite nice sounding in fact but the E is nowhere. I've tried re stringing a couple of times but its makes no difference. I'm wondering if it doesn't like thru body stringing? The bridge on my US '95 P is thru body only BTW. So, I replaced the offending E with a Dunlop where the difference is night and day. It blends nicely with the Elites and when the A,D&G newness wares off I think it'll be spot on and what I want to hear from my bass.