System Plateau - Ideas?

The last time I plateau’d was
Rega RP6 (Ortofon Black) > Musical Surroundings Nova II > Line Magnetic 518ia > DeVore O/93 

2 changes, more recently:
1. Switched amplification to
DeHavilland Ultraverve III (Dueland Special) > FirstWatt Aleph J
2. Also replaced Ortofon Black with a Hana ML.

Overall very nice, but I feel I’m missing a bit of “edge”.
One direction I’ve been leaning is single driver (researching Omega). Another direction would be rethinking amplification. Has anyone plateau’d here? What did you try?

Of course, everything sounds perfectly fine as is :)

Cheers,
John