Question about loading with an SUT

You left out “head amps” aka “pre-preamps” which have been around since the early 70s. These devices are active gain stages that boost cartridge output voltage ahead of the phono stage. They do not correct for RIAA. Sutherland and Hagerman make good ones but there are many other choices. When MC cartridges hit the US market in the 70s, most audiophiles owned only MM phono stages with insufficient gain to accommodate the MCs. Pre-preamps were the cure for that, even before there were many SUT choices. The good news is that a prepreamp will work with any MC, regardless of its internal resistance. So there are 3 viable options.

@chipcalzone , I'm using a Declare Z3 phonostage.

Thanks for all your responses. @atmasphere , this procedure is beyond my capabilities and leads me to consider a head amp.  In fact, many of the responses seem to be leading me in that direction.  I'm also good with the "don't worry about it" camp since I'm quite happy with the sound I'm getting.  Perhaps a Hagerman Piccolo is in my future but I think from this discussion, I'm going to rule out a different SUT since it seems they need to be tailored very specifically to the cart/tonearm cable and I don't want to have a different SUT for every cart.

A high gain phono stage can be an MM stage with an additional voltage gain stage tacked on to the input end. Such a topology can therefore handle both low and high output cartridges. Alternatively a high gain phono may simply incorporate a very high gain but unitary input voltage gain circuit.

I use five different carts and use one SUT currently wired at 1:10.

Perhaps a Hagerman Piccolo is in my future but I think from this discussion, I’m going to rule out a different SUT since it seems they need to be tailored very specifically to the cart/tonearm cable and I don’t want to have a different SUT for every cart.

It doesn’t need to be tailored, really. Any SUT in the range of 10x - 24x can be a pretty good general-purpose SUT for most low-ish to low-medium-ish MC cartridges (0.2mV - 0.6mV). Many SUTs also offer 2 taps, which is usually enough to cover "most" needs in an MC cartridge collection. Some even offer 3 or more taps - like the EAR MC-3 and MC-4 - these SUTs are extremely flexible, and sound great with almost any cartridge (excluding the high-output MCs, which are weird anyways).

If you do purchase a Piccolo (I’m a big fan of Hagerman phono gear in general), take note there are 2 versions: the Piccolo MC and Piccolo ZERO. The MC is a more traditional JFET-based "voltage mode" amplifier, with multiple gain levels and load settings. The ZERO is a "current mode" amplifier (a.k.a. transimpedance) that has "some" of the same considerations as a SUT - it won’t work well with cartridges that have high coil DC ohms. However, the Zero is spectacular on cartridges with very low DC ohms paired to efficient magnetic generators - like Ortofon SPUs.The Zero also offers 4 sensitivity levels (internal jumpers) for matching to a specific cartridge. I have a collection of SUTs, phono stages, and cartridges - and I love my Zero! It’s a big middle finger to the rest of the industry that Jim H. sells this for $270.

The Piccolo MC is also quite good by the way - I find Jim's JFET head-amps to be more "musical" than other JFET stages, at the expense of higher noise floor - a tradeoff that is acceptable to me. He does use very cheap SMPS units, in order to hit such low price points. There may be some gain in 3rd party linear PSU's.