Gain setting question for Ref Phono 2, Ref 3, Clearaudio Concerto cartridge

[Stumil]

Just bought a ARC Ref Phono 2 from a fellow audiophile/addict on AudiogoN to replace my ARC PH7. My pre-amp is a ARC Ref 3, amp Ref 110, turntable VPI Scoutmaster, speakers Vandersteen 5a. My phono cartridge is a Clearaudio Concerto with an output voltage of 0.8mV. My Ref Phono 2 has the following output choices:

Balanced High Gain: 74
Balanced Low Gain: 51
Single End High Gain: 68
Single End Low Gain: 45

Using Bob Harley’s formula from his book, the optimum gain would be 62db. Currently I’m running it at the balanced High Gain setting of 74 and things sound really great. I don’t think I’m overloading my ARC Ref 3 pre-amp, at least not that I can hear. I’m currently listening at a comfortable level with the pre-amp at the 21 volume level for vocals. I’ve been up as high as 50 for quiet symphonic passages. There is plenty of volume adjustability at low volume levels meaning that 1 on the Ref 3 volume scale doesn’t blow me out of the room. With the above facts, please consider the following options and offer some advice:

1) Do nothing. Sound is great, no reason to screw around.
2) Have my local ARC approved tech adjust the Ref Phono 2 gain down from 74 to something lower (is this possible, advisable, reversible?)
3) Run single-end instead of balanced which would lower gain to 68 from 74. Don’t I really want to run balanced though?
4) Replace my cartridge with a lower output cartridge?

Thanks - Stuart