high versus low output

The difference isn't really high output versus low output; it's moving coil versus moving magnet.

A cartridge consists of a coil of wire and a magnet. The stylus moves in the record groove in response to the vibrations in the record groove. When you move a magnet and a coil of wire relative to each other, an electrical current is generated. This contains the musical information that is amplified.

A moving coil cartridge has the coil attached to the sytlus. The magnet is fixed in the cartridge body. A moving magnet cartridge is the opposite. The magnet is attached to the stylus; the coil of wire is in the cartridge body.

Having a heavy magnet on the stylus can dampen the response of the stylus to the record groove vibrations. Having the coil of wire on the stylus makes it lighter so more vibrational information is picked up from the record. In order to keep the stylus light, the moving coil cartridge has only a few turns of wire. Therefore, output is less; therefore you need greater amplification.

A moving coil cartridge is superior to a moving magnet cartridge in terms of information retrieval. But the trade off is lower output. And it is more expensive to manufacture.

Some moving coil cartridges use more turns of wire to increase the output. These are "high output" moving coil cartridges. But you start to increase weight, like the moving magnet, and thereby start to dampen and mask vibrational information. It defeats the purpose of using a moving coil in the first place over the less expensive moving magnet.

So it isn't the low output that gives better quality. It is the more responsive stylus of the moving coil that gives better quality. The low output is just a byproduct of the lighter stylus assembly.

I went ahead and set up the Benz Micro Glider L. It plays at a lower volume than the Dynavector 10x5. The Moon LP 3 has a maximum gain setting of 60db. There are two options for capacitance setting, 0pf and 100pf. There is no difference in volume between these. What role does the capacitance setting play?

Tobias and Swampwalker described the reason why LO carts tend to be more responsive to groove modulations than HO carts. These differences are real and audible, provided you're comparing apples to apples (and not Benz's to Dyna's).

They also hinted at the techical issues you asked about without providing any details, so here goes...

Capacitance adjustment is for MM cartridges. It does not effect the performance of MC cartridges, which both of yours are. That's why you didn't hear any difference. Ignore this adjustment unless/until you acquire an MM cartridge.

The two critical phono stage parameters for MC cartridges are GAIN and IMPEDANCE. Each MC is unique in its requirements, so cartridge-phono stage matching can have a critical bearing on overall performance. The importance of this cannot be over-emphasized.

For impedance matching of an MC cartridge to an active phono stage like ours (ie, NOT a stepup transfomer), the rule of thumb is 25 times the internal impedance of the cartridge coils, + or - 50%. Every system is unique so experimentation is the only way to be sure of the "best" value, but anything in the above range will be close.

For gain matching of an MC cartridge, look here: KAB USA preamp gain computer.

***
For the Dyna 10x5 HO (2.5mv output, 150 ohms internal impedance)

- optimal impedance = ~1900-5500 ohms
Your SP3 has selectable impedance of 100 or 47K ohms. Try them both, but the 47K is likely to sound better. 100 ohms will give the cart a dull top end and a closed in feeling.

- optimal phono stage gain = ~42db
Your SP3 has selectable gain settings of 40 or 60db. Use 40db for this cartridge, 60 db is likely to overload your line stage.

***
For the Glider (0.3mv output, 12 ohms internal impedance)

- optimal impedance = ~150-450 ohms
Your SP3's 100 ohm setting will probably be best. 47K might sound a bit edgy or shrill (though it will hurt nothing to try both).

- optimal phono gain = ~61db
Your SP3's 60db setting should be about perfect. The 40db setting will produce lower volumes and perhaps lackluster dynamics even when you crank up the gain control on your line stage.

Read that twice. There'll be a quiz!

Swampwalker: thank you, thank you. I just hate it when that happens. Some
good person takes the risk of looking dumb and asks a fairly basic question
but he gets more confusion instead of help. 04rdking, thank you too for
emphasizing the point.

Valinar, I humbly apologize for my incompetently proofread response.
Swampy, if you agree, I would like to ask the OP and everyone else to
interchange "HO" and "LO" in my confusing post,
above, so that the relevant lines read

"The coils in a HO cart have to be larger to generate more
current,"

and

"A LO cart has smaller coils".

I am so glad to have a second chance to get that right.

Dougdeacon, thank you very much indeed for keeping me from putting my
foot in the wrong place over input capacitance. Using your limpid post, I am
going to work up slowly to the quiz.

Dougdeacon,
Thanks for your helpful response. I will study for the quiz. Hopefully you will allow cheat sheets.