Just got my Mani 2 today and compared it to my original Mani 1 with a decibel meter to compare the background noise they produce.
Using my Teac TN-400S turntable with AT100E cartridge, both pre-amps are in their original configuration (gain input H/output L) which matches the cartridge.
Using a Monoprice 1.5ft RCA cable from the turntable to the pre-amp.
With the turntable off and AV receiver on full volume,
the Mani 2 produced 3db less noise from my speaker's tweeter than the Mani 1.
Both were using the Mani 2's 16V 1000mA power supply. This was a direct swap so the cable runs did not move. The units were not stacked during testing.
That's a significant improvement in noise in my opinion.