I know this is kind of a crazy idea, but desperate times call for desperate measures and all that. What you need seems to me is a bit of line loss between the cartridge(s) and the phono stage. Do you have an extra long set of phono cables you could try? I have a set that I use for my subs, for example, that reach across the room. If you have something like that you might give it a try just to see if it helps. The guy I get all my wires from could make a set of special phono cables that would provide the mathematically correct amount of resistance to get the job done. If you have a guy like that you might give him a call. If you want my guy's contact info send me a private message.
"Recently, I have attempted to make sense of some conflicting measurements of the output voltage of various phono cartridges from different sources. The infamous one here are the measurements of the 2M Black in particular, comparing the results of HiFi World (HFW) with those of Miller Audio Research (MAR). I ended up emailing HFW and got a response from them that may explain the discrepancy.
To recap, HFW said the output of the 2M Black measured at 8.6mV (5cms/sec). From my email exchange, it appears they actually measured at 3.54cms/sec and "converted up" to 5cm/sec. MAR’s test said 5.79/5.73mV (L/R 5cms/sec). HFW thinks the difference is due to different test records (yes, I’ve experienced that) but also the differences between peak vs. RMS standards for measuring the output. Of course that wasn’t mentioned as far as I can see in either test result.Using a quick conversion calculator, it looks like 8.6mV peak voltage is equivalent to 6mV RMS. That’s pretty close to the MAR results, so this appears to make sense."
The next post says that HiFi World (HFW) probably erred in labeling their result "RMS". So their number should be divided by 1.414. In other words, the HFW value of 8.6mV is probably not an RMS voltage and is in other ways erroneous. Stick with the idea the 2M Black makes 5mV, like Ortofon says it does. Even the above explanation of why the HFW value is wrong is fuzzy.