balanced preamp

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.