XLR to RCA Adapters

I apologize for hijacking the thread, but I have a question:
What if the scenario was just an opposite- balanced preamp and single-ended power amp?
Would the Jensen type converter still be the best solution?
I understand, that if I used simple XLR/RCA adapter, then I would only use "half" of the balanced preamp circuitry?

I had Rogue Magnum 99 preamp and BAT vk200 for a month or so, but soon I replaced Rogue with BAT vk30.
BAT/Rouge (with RCA-adapter) worked fine (an improvement over Linn/Rouge which I had for a couple of years), but I just could not get away with the idea that all balanced approach would be better.
I like vk30 over Rouge except the phono. The phono card from Rouge sound better for me than the vk phono card.
Later, I got an RCA-XLR cable (from AudioQuest) and it worked better than with the adapter.
Now I have vk200 and vk60 with vk30, biamping Tyler Linbrook signature systems.

"When one considers the noise cancellation properties of balanced, then you can easily see the reason for superior audio. Less noise equals better sound. "

I auditioned Joule-Electra LA-150Mk2, then I owned LA-300ME for an year and now I am blessed with LA-450ME. All these preamps have balanced amplification in the gain stage but (except 450) their inputs and outputs are single ended i.e. Joule-Electra split single ended on inout and add on output.

As much as I tried to hear any (AMY!) noise when I place my ear to the speakers I hear nothing, nada, ziltch, zero etc.

I cannot remove noise I do not hear !!!!! I am sure theere are other SE preamps without producing noise and one shoyld be careful what kind of IC he has

Most "audiophiles" love word "balanced" without realizing the immense difference between balanced input/output and balanced signal processing (amplification here) which cancel not so much noise as DISTORTIONS !!!!!!!! and this make immense difference in distortion-free music presentation.

Of course there are many instances where hum is not a problem. I just like balanced because you never know when adding a component or a new light fixture or dimmer will create a problem.

08-22-11: Bob_reynolds
Mitch2,
Just curious... Why did you select an input transformer when your amps have balanced inputs instead of an output transformer, like Model DM2-2RX?
Wouldn't it be theoretically better to have shorter RCA cables at the preamp and longer XLR cables to the amps?

Bob, that's an excellent question.

I'm not entirely sure of the answer, but I believe it relates to differences in inter-winding stray capacitance (i.e., between primary and secondary) of output transformers vs. input transformers. I've noticed that the schematic representations of the Jensen input transformers that I've looked at all show Faraday shields, which would greatly reduce that stray capacitance, while none of their output transformers that I've seen include those shields. I have no particular knowledge of why that may be; presumably it has some relation to the fact that output transformers have to be able to drive much longer cable lengths.

Lack of a Faraday shield in the output transformers results in very substantial inter-winding capacitance. For instance, the this output transformer is spec'd as having 22,000 pf of capacitance between windings, as measured at 1kHz.

A result of that capacitance will be that the input stage of the amp would see, "looking back" at the output of a preamp + output transformer combination, an impedance which is very unbalanced between the two legs at high frequencies (since one side of the transformer primary is connected to preamp ground, while the other side is not). That imbalance will significantly degrade the cmrr of the amp's balanced input stage, at the high frequencies for which that capacitance becomes significant.

Hopefully someone more knowledgeable about transformers than I am will comment further, but I suspect that the explanation is along those lines.

Best regards,
-- Al