the XLR inputs on your Yamaha are pre amps. if you use an external pre amp, they should be bypassed.

Most likely the XLR are low impedance and the 1.4" are high impedance.

Brian Sansone, post: 464333, member: 50010 wrote: I have an old yamaha 3210 monitor mixer. It has low z 1/4" inputs, and hi z XLR.
From a post here, asking about the mixer, I learned the mixer can handle low/high z input, has pre amps, and was built to deal with the different signals.
Sooo... I was looking today at some 500 rack pre amps. Would one benefit me? Would I still run the pre amp signal through the mixer? Or does that defeat the purpose; by adding the coloration of the mixer amps?
Would I use the pre amp signal to go directly to my computers interface?

Thanks
Brian

So the quick answer is : you already have preamps..

But if your Old Yamaha isn't giving you the sound that you expect, Yes an external preamp could be the answer.
(hopefully the sound you don't like do not come from your room, your mic or bad placement)

What you shouldn't do if you buy a highend preamp is connect it to the Yamaha mixer.. A preamp in a preamp just degrade the quality of the highend one (unless for special effects, saturation etc)
If you record with a computer you should have a proper audio interface (with included preamps or not).
Most quality interface will have line ins input that go directly to the converters.
Usually those are inputs without gain knobs. (a gain means some amplification circuit is present so it can color the sound)

A 500 series rack is great because you can mix and match different units.
Other than that, you can check ISA preamps for just a thinny bit of mojo but very clean 80db.
Or check the UA 610 who can be clear or go to saturation if pushed.
Other clean preamps : Millennia, Grace audio, Daking, Manley.. all different flavors (for those who can hear the difference) ;)

The TRS channel inputs on the MC3210M are medium impedance (10K Ohm) and the XLR inputs are a bit lower (5 K Ohm). They are effectively connected together internally and pass through the same pad and pre-amp. By contrast, the insert returns bypass the pre-amps, but are unbalanced. However, the maximum level at the insert return (TRS ring contact) is a useful +20dBu.

Based on that, my suggestion is that you consider by-passing the Yamaha input circuitry by using external pre-amps that have either floating transformer outputs or have electronically balanced outputs to feed the mixer's insert returns. When correctly cabled, both of these will give their full output into either balanced or unbalanced receivers. Examples are the API3124+, the UA models or the Focusrite ISA range. An alternative would be to go for a standard balanced output (non-floating) pre-amp, followed by a UA1176 (or the Warm Audio WA76 clone) for compression/limiting duties coupled with some real transformer heft. I was amazed at the difference I got when I took this route with a Yamaha O1V96.

But why use the mixer at all? What model of Audio Interface do you have?