Preamps with Dual XLR Outputs

That Topping is a pretty impressive DAC!

:)  Sheesh.

@bdp24 Well there you have it. A transformer with a dual secondary so that the single-ended and balanced connections can't mix. The upside is that both connections can be supported at once; the downside is there is additional capacitance due to the presence of the second output winding. This probably does not affect bandwidth much on account of the transformer being fairly low power. Note though that it is designed to support the low impedance aspect of the balanced standard; the 1K resistors @almarg mentioned are there to load the transformers to prevent ringing if used with a load of higher input impedance.

One exception to atmasphere's comment directly above is a pre-amp using a transformer to create the balanced output(s). That's exactly how Tim de Paravicini does it in his EAR-Yoshino pre's. There is an EAR 868PL (phono and line stages) listed on Audiogon at the moment, and it has two pair of both XLR and RCA outputs.

Actually if a transformer is used, it has to have a switch so one side of its secondary can be tied to ground in case the output is to be single-ended. So a switch is required.

The only way to do balanced otherwise using a transformer and no switch is a a transformer with a center-tap. But this would sacrifice a lot of common mode rejection performance since the center tap can't be exactly placed at the center of the transformer windings. which is why no-one does it that way (as far as I know).

@yyzsantabarbara  If supporting the balanced standard is important to you (it results in better sound...) one thing you can look for on any balanced preamp is whether it has RCA outputs as well. If there is no switch to go between the balanced operation or single-ended, then you can conclude that the preamp does not support the standard.


The switch would be used to sort out the ground issue. If there is no switch that means that all the outputs of the preamp reference ground and so ground is used to complete the signal circuit.

am not sure if a tube preamp would work well with the Yamaha NS 5000 speaker. I am also not sure if I would get the benefit of super low noise floor of the Benchmark AHB2 with a tube preamp.

@yyzsantabarbara  A good tube preamp had better not be a tone control! It should just be neutral. This is not a bandwidth thing either- for example the line stage our our preamps goes out to about 400KHz- higher than many solid state preamps. The thing here to be aware of is the brightness of solid state is not on account of frequency response; just about all preamps tube or solid state will be nice and flat in the audio band. The brightness of solid state is the result of distortion, and really not a lot of it because of how the ear works.

The ear uses higher ordered harmonics to sort out how loud a sound is and because it has a range of over 120dB, it has to be very sensitive to higher ordered harmonics. So if a circuit makes higher ordered harmonics even in very small amounts it gets interpreted by the ear/brain system as brightness and harshness. We are talking about THD that might only be 0.005%.


That is different from simply being neutral. Your Yamaha speakers might be easy going on top, but if you put something extended that is also neutral this will not cause them to sound rolled off!

Regarding noise, its nearly all power amps are lower noise than a preamp. Yet people use tube preamps in systems with **horns** all the time; your Yamahas are not as efficient as horns so you've got no worries in this department :)

@yyzsantabarbara

The Atma-Sphere MP-3 and MP-1 both have dual balanced outputs and no worries driving low impedances. FWIW Atma-Sphere made the first balanced line preamps anywhere way back in 1989.

A tip: If your preamps supports the balanced line standard also known as AES48 (Audio Engineering Society file 48) then you will have the ability to drive longer cables without coloration, and less coloration from cables in general. You will also have less likelihood of encountering a ground loop. This will allow you to place the amp right by the speaker if you want, allowing you to run a shorter speaker cable. You also won't have to spend as much on the interconnects!