balanced preamp

I currently own a First Sound deluxe MK11 and would like to
Try a balanced pre to my Mark Levinson 336.
Those of you who have made such a change,what has been your experience?
You might want to consider the Atma-Sphere MP-1 (2-box) or MP-3. Both can be ordered with a (absolutely sensational!) fully balanced differential 3-stage tube phonoamp. My amp is a McIntosh MC275 (tube) -- and since tube sound vs. ss sound is a function of the amp (and not the preamp, imo) your sonic result will be different.
I wouldn't make a selection using balanced as the most important factor to consider. I do feel its better but I would buy a component based on sound quality first. If it just happens to be balanced, thats OK too.
When I went to balanced connections with my ML 433 I was quite happy with the result. If a company goes to the trouble and expense of a fully balanced option, like your ML 336, it is likely to be the best option. But, just because a unit has XLR connections doesn't mean its fully balanced.

My ARC LS 27 and ML 433 sounded better even with cheap balanced cables than they did with expensive single ended.
Going internally balanced is a good way to reduce distortion of the circuit. This is true whether the preamp is tube or solid state.

If the balanced operation is done properly, the interconnect cables cease to be a part of the sound of the system, unlike single-ended. Note the caveat 'done properly'.
Although MANY great designers don't care about balanced operation (Conrad Johnson, etc.), I do. The solidity of XLR connections and the low noise/impedence has served me well in pro audio, and I was wondering aloud (here) about what was out there when the Kavent dude contacted me. I bought one of their S-33s (exactly the same preamp as a Vincent SA93, just different cosmetics) and am utterly amazed at how good it is, and it matches well with the XLR inputs on my Jolida 502p (and a Forte' 55 before that). Unfortunately the Kavent people have disappeared, but my preamp happily remains...a fully balanced design all the way through.
Atmasphere, Fully balanced configuration reduces only even harmonics while leaving odd harmonics intact - I'm not sure if it sounds better. In addition gains have to be perfectly matched or common mode interference would get converted to normal mode signal. It also seriously increases cost - could buy much better non-fully balanced preamp.
Thank You all for your helpfull replies.. I have tried my P.S.Audio PW DAC 11 via the Balanced out directly to the M.L.336 and was impressed with the results, I do not want to take a step back the First Sound pre does a lot of things right.. I have aways enjoyed a tube pre but find more solid state balanced pre in the market.
Atmosphere I am not sure if there is a dealer near me nor have I had a chance to hear one of your pre's
Kijanki, you are correct about the distortion product. However the less distortion is made the better. If you do the design right, the primary harmonic to show up will be the 3rd. If you don't, you'll have a mess on your hands :)

I don't find in practice that cost is much of an issue. If you are to build a world-class preamp, it will have to have good power supplies whether it is balanced or single-ended. All the things you have to do to make a single-ended preamp really work right cost about the same.

In practice I've not found your comment about gains being perfectly matched to be correct. I've seen minor differences that show up if you have unmatched tubes and the like, yet the CMRR is still quite good (there is a lot to be said for a good CCS design!). If the preamp were balanced but not differential then you might have a point.
Atmasphere, If preamps are balanced and differential then at the spot where summing takes place (input of power amp or speakers) common mode interference will appear as signal. For instance, if one leg has gain of 30 and the other gain of 30.3 than your gains are mismatched 1% meaning your CMRR is limited to poor 40dB and 1% of junk goes thru. We can take for comparison input module in my Rowland 102 with THAT1200 instrumentation amp (instead of transformer) with CMRR=85dB (DC-20kHz).

Many people like warm sound. Removing even harmonics might not to be to their liking. Main beef is with odd harmonics that are left intact (perhaps not big problem in tube amp).

In case of your amplifiers - power supply has to be way heavier while number of tubes and output transformers and expensive capacitors doubles, chassis gets much bigger etc. It should cost a lot more. Your amps are state of the art and might not meet objectives of typical person (most bang for limited bucks).
Kijanki, we don't have any output transformers so we don't have that expense anyway...

Is it me or is 85 db a poor CMRR figure?

Like I said a lot depends on an effective CCS circuit. I have to say I am quite surprised to see how poor they are in most differential circuits I see. Poor CCS leads to poor CMRR response! You can't do it with a single-stage CCS...
Atmasphere, 85dB is decent especially when you take into account effect of twisted pair rejection, in addition to shielding, in XLR cable. In order to match 85dB rejection in fully balanced amplifier gains would have to be matched to 0.005% - not possible IMHO.

I forgot, you have no transformers but you have a lot of tubes. Not only cost of tubes but they also require more power.

"I have tried my P.S.Audio PW DAC 11 via the Balanced out directly to the M.L.336 and was impressed with the results, I do not want to take a step back the First Sound pre does a lot of things right.."

Theres absolutely nothing wrong with wanting to go balanced. Most of my components are. After reading your above post, though, I can't help but think that there is a lot more going on as to why you are hearing differences besides the PS Audio being balanced. The 2 units are very different from each other in many ways. I'm just suggesting that there are other factors that make them sound different besides being balanced.
Not only cost of tubes but they also require more power.

Where are you going with that?? That does not have anything to do with CMRR... and is not accurate. The tubes we use are not expensive, and usually cost less than a set of tubes for a transformer-coupled amp of the same power.

From your other comments though it really sounds like the circuits you are used to measuring have poor CCS circuits. 85 db is not a hard figure to attain.
Yes Time for a change I would like to try a good balanced pre, even my phono pre will run balanced... My Question should have asked prior Frist Sound owners where they moved on to (in regards to a new BALANCED preamp) and did they improve their system.
Atmasphere, We were talking about cost of fully balanced gear. I expressed opinion that in order to get fully balanced amp or preamp you pay more and sacrifice CMRR (since you cannot keep gains equal to 0.005%) - whole thing to remove even harmonics that most people don't mind while leaving odd harmonics intact. I suggested to get better standard amp/preamp instead.

As for 85dB being easy to do - please notice that CMRR of line input transformers is shown at 60Hz. 85dB at 20kHz is pretty good number for any instrumentation amp. In addition line input transformers introduce distortions at low frequencies.
OK Kijanki, I will take the other comments as a red herring then.

From your comments it seems to me that you are used to working with balanced gear that uses the ground connection. The ground is supposed to be ignored. But a lot of balanced gear uses it, which degrades their CMRR. I see this all the time in high end. Unfortunately, lots of instrumentation amplifiers have this same design flaw.

However, single ended preamps have no distortion cancelling capacity, and nothing for a CMRR. This is not saying that they can't sound good by any means, but it does mean that they are prone to interactions with the interconnect cable, something that should not happen with balanced operation.
Atmasphere, It seems that fully balanced configuration offers benefit of even harmonics reduction at some expense of CMRR. I can understand that it might be too expensive to manufacture to stay competitive at the lower/medium price range but all your amps are fully balanced (I think).

I often see opinions that XLR cable offers no benefits without fully balanced configuration. Nothing can be further from the truth. Not only that balanced input has common mode noise rejection at the order of 85dB+ (nothing to sneeze at) but also twisted pair (in addition to shielding) has huge rejection especially at audio frequencies (where wavelength is much longer than twist density). In comparison single ended gear has only protection of the shield and, as you stated, zero CMRR.