Balanced outputs vs balanced design

Friends, I am looking for a balanced tube pre to mate with Halcro MC20. I have since learned that there are single ended designs with balanced outputs and fully balanced designs, like the BAT's. In a response to a thread below the author suggests that the "magic" happens in the amp and that the pre does not have to be fully balanced to benefit from the noise reduction qualitites. If so, is thre any inherent advantage to a fully balanced preanp? And more particularly for my purposes which would not run connects more than 10' from the amp. If there is no great advantage to a fully balanced pre, I can widen my search. As always, tell me about your favorite tube pres to run with this SS amp. Many thanks.
fully differentially balanced amp and pre amp is the way to go. less noise darker background better sound stage and detail. just better all together. you will pay more for a fully differentially balanced piece of equipment there are more parts and it is a lot harder to accompilsh if done well. i would look at the montana audio site
I second Wwshull's comments. If your amp is fully differential, you will not be getting the most out of it unless your whole chain is fully differential as well (source and preamp). You cannot re-create what has been eliminated.
FWIW, my personal favorite fully balanced preamp is the ARC Ref 3.

Defintitely DB all the way! First Overture would be worth considering as a preamp. It is also a SOTA DAC.

I have a PS Audio GCP/GCPS. Very reasonable price. It has passed through every change I have made to my system.
Balanced interconnects between preamp and power amp are inherently less sensitive to noise pickup in the wires...that's why the pros use them for long runs. However, in the typical home environment with relatively short runs good quality single-ended interconnects don't have a noise pickup problem.

As for balanced circuitry in the power amp the advantage over single ended is largely theoretical for well designed equipment. It is often said that balanced is quieter because the signal is twice as strong, but there is also twice the circuit noise. Common mode noise, as for hum from the power supply, will be canceled, but there shouldn't be any such noise in a good unit.

I have balanced interconnects in my system, but only because the equipment I use has this interface. I think you should select your equipment on the basis of how it sounds to you. Balanced configuration has some advantage in certain cases, but, IMHO, it is sold, at considerable cost, to audiophiles who don't need it. It mainly gives you bragging rights.
my favorite fully differentially balance equipment is maid by montana audio
Eldartford is correct; choose your components on sound alone, not whether or not they are balanced.

Some of the finest high end manufacturers build only single ended equipment.
I own a ARC Ref 3; it is a fabulous differentially balanced linestage, with loads of finesse, micro and macrodynamics; I suspect it will match very well to your Halcro. . I am also exceedingly partial to amps manufactured by Jeff Rowland Design (JRDG) like the Concerto. I have heard it matched to several Rowland power amps--which like yours are class D switching amps--and the results are supremely musical. . . . and yes, Rowland preamps are all completely balanced designs.

An other linestage I have enjoyed very much and may in fact soundly slightly sweeter on the Halcro MC20 than Ref 3 is the VTL 6.5 Mk2 hybrid. . . still a truly balanced design and truly magnificent. Were I now in the market for a linestage I would consider this device extremely seriously as well.
By the way, tell me more about your experience with the MC20: Strong and weak points? what other amps did you consider? Any other digital amps in the race? What tipped the scale in favor of Halcro MC20?
Friends, thank you for the replies and suggestions. I will check out the preamps recommended, though it is apparent that they are a pricey bunch. I think that a used BAT 5VK is more in my price range - or perhaps a used Atma sphere. Missed out on a very well priced one on Ebay (just over 2k). Drats.
Guidocorona, I wish I could tell you that my path to the the Halcro was the culmination of an exhaustive trial of many contenders. But the fact is that I was looking for a beefy amp to drive a pair of Gallos that I was interested in and read a few very flattering reviews of the Halcro which packs a punch at 400 wpc. I also wanted an amp that does not pump out the heat like my Pass Aleph 3 - the "little furnace." I am a musician and was drawn to the transparent qualites attributed to the Halcro as well. Never figured I'd end up with the Halcro given the $5k price tag. But I got a lightly used demo with warranty from a dealer for $2400 on Ebay. It arrived yesterday and have not had a chance to plug it in. My current system is a Pass Aleph 3 and Blue Circle 21 powering a pair of Newform Balance speakers. It will be interesting to hear the difference between these two very different amps. My plan is to build another system, using the Halcro to push the Newforms which are not terribly efficient. So I need the pre for that Halcro set up. And then I will get a second pair of speakers for the Pass/BC. On the short list are Gallos, Tyler Signatures, Salk HT3's, Zen Adagios, or a Zu product. Not such a short list now that I see it in front of me. Unfortunately I live in rural Maine and do not have the luxury of ears-on trials. But I bought the Pass/BC/Newform unheard and have no regrets. I appreciate any thoughts y'all may have on the speaker end. There are those used Zu definition Pro's that look very nice.....
im wondering if a set-up offers single ended and balanced ins and outs can it be fully balanced? my reason for asking is i have a cairn nitro pre and ko2 amp with a fog 3 cd player . great sounding stuff , but they are the very vague with the spec's , and seem to be some of the least reviewed gear ever. but i do love it fully balanced or not.
ELDARTFORD: As for balanced circuitry in the power amp the advantage over single ended is largely theoretical for well designed equipment. It is often said that balanced is quieter because the signal is twice as strong, but there is also twice the circuit noise. Common mode noise, as for hum from the power supply, will be canceled, but there shouldn't be any such noise in a good unit.
Circuit noise is not twice as strong (+6 dB) in balanced designs. Rather, it's +3dB stronger, due to stochastic signals adding up logarithmically. That gives balanced units a +3 dB advantage in noise over single-ended ones. You are also neglecting the benefits caused by reduced distortions caused by cancelling, as well as the improved stability at the power supplies. The advantage is largely theoretical for BADLY designed equipment. In well designed units, the advantage is subtle but real, and I think detectable by ear if you care enough.

11-18-07: Jrw40
im wondering if a set-up offers single ended and balanced ins and outs can it be fully balanced?

Can it be fully balanced? Yes
Does having balanced in's and out's mean it has to be fully balanced? No.

Some manufacturers offer balanced inputs and outputs for convienience, but they tie the negative (-) leg to ground inside the chassis and have single ended internal circuitry, not that there's anything wrong with that. However, the appearance of XLR connectors on the rear apron of the unit does not necessarily mean it is a fully differential unit. For it to be fully differential, it must have mirror interior circuitry for both the positive AND negative legs. This can become pretty expensive, and the results are not always audible. Hence I would say that most equipment is single ended, though some single ended gear will have balanced inputs/outputs.

There is little technical info on the internet about Cairn gear, but from what I can find, it looks to be a single ended design with optional balanced inputs and outputs.

Neither the preamp nor the amp are required to be "fully" balanced to gain the advantages of common mode noise rejection at the interface between the two. Both components can be an unbalanced design with proper (active differential amp, transformer, or IC) balanced inputs and outputs.

A proper balanced differential input at the preamp will cancel any common mode noise picked up from the source to that point. A proper balanced differential input at the amp will cancel any common mode noise picked up from the preamp to that point. Are there advantages to maintaining the signal balanced throughout the amp (or preamp)? I can see that if each subsequent amplification stage were differential in design, then they would cancel intra-amp common mode noise. I have no clue how much of an issue this could be or if there are other advantages.

The effectiveness of a balanced input at canceling common mode noise is a matter of implementation. So, obviously, not all balanced inputs are created equal. According to Bill Whitlock, the CMMR of a balanced input circuit is determined by how well the impedance between the signal conductor and the ground conductor of its two inputs match.
The advantage of a fully differential preamp or amplifier is that distortion is canceled at every stage in the device. As a result fully differential products can be lower distortion for a given amount of gain. Noise can be lower too- and the effects of noise and distortion always compound from stage to stage. The more differential circuitry is used, theoretically the more transparent the preamp or amp will be as well.
Jmaldonado...Yes. As you say random circuit noise in each leg will appear at 1.414 amplitude at the differential output, wheras the signal will appear at twice amplitude. So there is a bit of noise reduction. S/N of my power amps is spec'd at <100 dB, and the source equipment is better. I'm not sure what another 3dB would buy me. As for distortion, there really isn't any to cancel.

The more even loading of the two rails of the power supply is a real benefit IF the power supply design is marginal.
Some amps are spec'd for power, both channels driven, with the two signals out of phase (like a balanced design amp).
Eldartford, its likely that your amplifier has a lot of differential circuits already- many transistor amplifiers do.

There is more than one stage of gain in most transistor amplifiers, so you get more than 3 db on the noise figure. Doubtless that is part of why your amp is as quiet as it is.

The area where the technology is still under-utilized is preamps (tube and transistor) and tube amplifiers.
Don't forget to look into a balanced power system or at the very least dedicated power lines to ensure these units are getting fed clean and consistent power (i.e. harmonic + noise free and consistent voltage = 120v) otherwise you are only looking at one 1/2 of the equation.